This is a guide specifically for the map 'Laser Bridge' - and more importantly the 'Fiskeplaske' boss. Before I delve too far into the actual strategy, and map layout; let me first forewarn you not to take this level lightly. With a basic setup, it is quite easy to reach the final wave, only to fail miserably in a matter of seconds to the boss.
For starters, ensure that you and your teammate(s) are all level 30. Access to some important perks are locked behind the later levels, so don't handicap yourselves by attempting this map too early. Another important fact is, while technically possible, it is 100% NOT
recommended that you attempt this map solo. Take this from my tortured experience; coop is the only way.
EDIT: For those masochists out there, here is a character setup that I had attempted several times solo, that allowed me to reach the boss wave by myself. I never managed to actually kill the boss this way, as I didn't have access to every tower and perk that are pretty much mandatory in beating this map. The cold truth is that this map is nearly impossible to beat solo.
Now, pick classes that you and your partners are most comfortable playing as, and not classes that you think
will be most effective against the boss. Now for some hypocritical advice: pick at least one Sweet Autumn. The more people in the game, the more devastating the enemy health becomes. Sweet Autumn has a very important passive ability in her lasting burn damage, that also circumvents enemy health regeneration. This is crucial in dealing quickly with mobs that the later-explained lasers cannot.
I'll get into exactly which perks should be taken with which possible characters you happen to choose, but first I'll explain the parameters of fighting the boss itself. The Fiskeplaske is a slow-moving flying boss that 100% completely ignores tower damage, and player damage that doesn't hit one of its 4 weakspots. The catch, is that it only ever has one weakspot active at any one time, which constantly rotates to either its mouth, under its right and left wings, and its back. As you damage a weakspot, it eventually rotates to another position at random. This is hands-down the most frustrating aspect of fighting this boss, because this can often lead you to running straight into a cluster of mobs that quickly kill you.
I have found two ways to effectively combat this issue with the boss (one in theory anyway), but only one has ever been executed without a hitch. You can choose between building fast-running, hard-hitting "mob/boss killers", that rely heavily upon player skill, tactical placement of your standing positions, and focus entirely on offensive perks; or you can build a careful setup of specific classes, both offensive and defensive perks, and towers that ensure more stability when fighting the waves before the boss, leading to better circumstances under which to actually fight it. The first strategy can be highly enticing for veteran players, however the more people in a lobby makes this strategy much harder to actually execute, due to the high rate of potential player error. If you trust your partners to execute their roles flawlessly, pick this strategy; if not, I'll detail the other below, shortly.
Now on to towers. Depending on how many people you have in your party, you may not have access to every possible tower. Because of this, I'll list the most important towers in a list of 1-12 (1=best):Focus Tower
(The bread and butter of most maps in Sanctum 2, this tower should always always be in your inventory)Range Spire
(With this tower, you effectively double the range of all surrounding towers, which allows them more time to kill mobs before reaching your core. A MUST)Drone Tower
(Deceptively powerful, these drones are your best bet against fast moving, highly-armored mobs. Rhinos, Bobbleheads, and Heavies beware)Slow Mines
(Built next to a Range Spire, these individual mines make for a constant slow field throughout much of your maze route, effectively reducing enemy speed by nearly half)Kairos Tower
(Not as important as Slow Mines, however, this is the only tower available in the game that has any tangible effect on the Fiskeplaske. If placed next to a Range Spire, the Kairos can actually slow down the boss further, saving you precious seconds to deal more damage to the boss before he reaches the core)Amp Spire
(If enough resources are available, this, paired with a Range Spire can effectively improve the damage output of all surrounding towers by upwards of 35%)Lighting Tower
(The only tower that can hit multiple mobs at once on both ground and air, this tower is never without its uses)ACP Mine Dispenser
(While not technically necessary, the more people in the lobby allows for more resources to be spent on towers like this. Build and upgrade this in the very early rounds, and stockpile all the mines for each subsequent round until the very last round. Then, place a mine throughout your entire maze, at around 3 mines per row, effectively reducing many of the actual mobs that you need to fight during the boss battle)Make-Shift Cannon
(These quirky little towers are inexpensive, and provide a rather powerful side-effect in occasionally stunning mobs for a few seconds. The down-side, is they can also stun themselves, effectively cutting down their potential usefulness when not placed in bunches. A fair enough tower, but not mandatory)Rocket Tower
(These are nice in that they can do significant damage to whatever mobs they hit, but their infrequent firing isn't often worth the damage that they do. A tower that has its uses, but not very many)Scatter Laser
(Another tower that doesn't do enough to justify its already low-cost, this tower can be useful for certain waves, but unless placed in bunches; doesn't possess enough upside to bother)Violator
(One of the worst towers in the game. While this tower has the single-highest damage output of any tower in the game, its extremely slow firing rate makes the resources spent on this expensive paperweight better spent elsewhere)
Pick and choose from these towers, but the first 8 or so are - in my opinion - the best bet for beating this map. Now on to perks and characters...
Again, depending on however many players you decide to go with for this map, there are always certain characters that should be chosen over others. Sweet Autumn is, again, the best all-around choice for handling mobs, and combating the boss, so always make sure AT LEAST one Sweet is present at all times (if playing with 4 players, pick 2 Sweet Autumns, as her passive burn damage is poorly offset by the large increase in enemy health due to more players). Tysgan is often your second best choice, as her high offensive output and fast running speed makes her ideal for kiting and killing individual mobs. Her passive shot damage bonus is also highly effective against the Fiskeplase's weakspots.
SiMo is an obvious choice for many due to his high bonus damage vs. weakspots. However, I found his slow movement and lack of overall damage output to regular mobs to be too offsetting for picking him for this map. That's just my opinion, as others may find him preferential to other classes and playstyles. Skye Autumn and Haigan are both largely ineffective for this map, so unless you possess God-like skill and precision with them, play as someone else.
I'll layout the suggested classes and perks, but it's entirely up to you who and what you pick:Pure-Offensive Class #1:Sweet Autumn
(Use secondary fire of the REX launcher on multiple, slow-moving mobs that are far away, and primary fire on closer, more armored enemies. A charged secondary Balista shot is devastating when shot directly in to multiple mobs, and the charged primary fire is very effective against Bobbleheads)Exposure Rounds
(Paired with Sweet's passive burn effect, this perk actually ends up lasting as long as the burn effect, making it even more powerful)Fast Hands
(Fully emptying your clip should be standard anyways, so why not add an almost permanent 30% damage bonus to it?)Long-Range Specialization
(This is where things get really awesome for Sweet. If you position yourself behind the core on top of a set of cargo containers, you effectively add an insane amount of distance, thus explosion size to all of your shots. Paired with Exposure Rounds, and Sweet's already passive burn damage, you are almost always hitting 50-60% of all mobs on the map at once. A very effective setup)
*At some point it slipped my mind that instead of taking the 'Fast Hands' perk, you may wish to try the 'Slow Rounds' perk instead. I've never tested it, but given that Exposure rounds increase in duration due to Sweet Autumn's passive burn effect; this may also transition over to an increased slowing duration. Again just a theory, so attempt at your own risk*Pure-Offensive Class #2:
Hollow Point Rounds
(As Tsygan already receives a massive damage bonus for the last shot she takes, this perk effectively makes her an absolute monster for killing off mobs quickly. No other perk has this big of an effect paired with Tsygan)Fast Hands
(As you'd be playing as a very fast-firing and fast-moving class, it makes sense to gain as much of an advantage as possible. If you're a true pro with this class however, this perk slot can be interchanged with the "Marksmen" perk, assuming you're extremely effective at hitting weakspots consistently)Corpse Explosion
(This is an extremely underrated perk that often gets overlooked for pure damage-increases or defensive core perks. The idea behind Corpse Explosion is the more enemies you, the player are actually killing, the more mobs you'll then kill afterwards. Great for taking down multiple mobs hitting the core at once, though the focus should always be on the enemy with the largest health bar to receive the most tangible bonus for this perk)
*This class is best employed at close range, so that it can be used to kite the biggest set of mobs.*
While the above 2 classes are extremely effective at this map, the harsh reality is that because you'd be playing with the 5 Feats of Strength enabled, you leave an awful lot to chance by not taking the "Phoenix" perk. If you are truly not worried about dodging mobs - and more importantly, the missile barrage attack from the Fiskeplaske, then don't worry about it. Otherwise, you may have to sacrifice a damage perk for Phoenix.
While in a perfect world you'd love to have a team comprised of nothing but these offensive-minded classes, you'd be hard-pressed to actually complete this map without taking a few defensive perks as well. Through some combination of the previously suggested classes, you need to find a way to incorporate at least one of:
Resilient Core stacks, so for each player with the perk, an additional 10% of core health will be restored. However, only one player should actually take this perk, as your strategy shouldn't be reliant on the core taking any health at all. Always ensure someone takes Shocking Revelation at all times.
Now for those pesky Healers
Mutators should almost always be your primary focus. Their relatively low health makes them easy to kill if you focus on them specifically. Only when faced with multiple Walker Warriors
should you focus elsewhere. Healers can be annoying, but a couple lock-ons from Sweet's REX-Launcher should make short work of them.
Finally, we reach the actual maze layout itself. There are multiple ways of building an effective maze, but very few that effectively make use of the stationary lasers scattered throughout the map. You'll notice these lasers as they're right next to big green flashing buttons that are activated by shooting them. Make use of these lasers whenever a large group of mobs are in their direct path. It's also a good idea to place individual Slow Mines along their paths' so to trap as many mobs as possible in their damage radius.
I'm unsure of how to actually embed images into solutions, so follow this image link, and get a basic idea of what kind of maze you'll want to build. The one below was the one I found most success with:
*Let me add some clarification to the above image: Start the building of this maze at the front of the mob spawn side, rather than the core side. I also prefer to invert the layout of the maze, so the mobs end up entering the beginning from the right side, rather than left. This saved me precious seconds when activating the first laser. Also ensure the entire route up to and including the 2nd horizontal laser (on the right side) is fully built by the start of the 3rd wave, as this particular laser is best used to take care of the excess Bobbleheads.*
On the second line, closest to the mob spawn, I find it important to build a couple of Focus Towers, a Range Spire on the little protruding block, a Slow Mine Dispenser and Drone Tower next to it, and a Lightning Tower right at the end next to where the first Laser would reach. Before building anything else, build a Focus Tower way back directly in front of the Core (on the block either to the right, or left of that middle block directly in front of the Core). You'll eventually build a Range Spire and Kairos on that front-middle and either the left/right side (whichever you didn't build the Focus on).
The third line (closest to the mob spawn) is where you'll want to build more Drone Towers, and an AMP Spire (make sure the Range Spire is within range of where you place an AMP to maximize effectiveness). Save a little room in the dead center of the map for another Kairos Tower (if the Kairos isn't effected by any Range Spires, build another one next to it, along with another Slow Mine Dispenser).
This probably sounds extremely confusing, so I'll clarify everything into a comprehensive, smaller guide here:
*After building each damage-dealing tower, ensure you set their passive behavior to "Most-Health". This allows your towers to make short work of the strongest of the enemies. Before the final wave, be sure to set back all the behaviors of your towers to "Lowest Health". Realistically though, most of your towers will get fixed on shooting the Fiskeplaske, so there isn't much to be truly done here. Make sure you keep your Kairos towers set to "Highest Health", as they will then focus entirely on the Fiskeplaske*
Step 1: Build Focus, Drone, Range, Slow Mine, and Lightning on the second line closest to the mob spawn.
Step 2: Build Focus, Range, Kairos towers on the first line in front of the Core.
Step 3: Build Drone, AMP, Karos Towers on the third line closest to the mob spawn (ensure all of these are effected by the Range Spire of line #2)
Step 4: Build Kairos (and possibly Range Spire) on the line above the first one closest to the Core.
Step 5: Ensure all towers on the map are 100% fully upgraded to level 3 before building to the 15-tower limit. Additional Drone, and Focus towers should be built that are most effected by Range and AMP spires.
Step 6: Ensure all Kairos towers are built in the middle of their respective rows, so to best effect the Fiskeplaske.
Step 7: Ensure the 1st and 3rd rows (closest to the mob spawn) are completely covered in slow mines, so the entire route is drenched in a permanent slow field.
Step 8: ????
Step 9: Profit
Some of this guide may end up being too vague in certain areas, so please post in the comments on any of the areas you'd like additional clarification. For those who would like to read more about all aspects of Sanctum 2, here's a link to a comprehensive guide for which much of this information comes from. I take no credit for the guide below: