To get the complete 100%, you need to complete the following tasks:
1) Complete all the story missions - [story related]
2) Complete all side missions and secondary missions
3) Free all 120 Bound Serpents - [see collectibles section below]
4) Complete all 24 stunt jumps - [see collectibles section below]
5) Visit all 32 vista/landmarks - [see collectibles section below]
6) Find and view all 13 legends - [see collectibles section below]
7) Learning all 12 solos - [see collectibles section below]
8) Raise all 11 Motor Forges - [see collectibles section below]
9) Purchase all 47 upgrades and paint jobs from the Motor Forge
10) Raise all 24 Buried Metal Shrines - [see collectibles section below]
11) Unlock all songs - [raise all of the Buried Metal Shrines and complete the game]
12) Unlock the Concept Art - [see Concept Art section below] - There are 83 pieces of concept art in the game but you only need the 17 Ironheade concept art to get the achievement.
The best resources that I have found so far is from Achievement Hunter (kudos to those guys, it's a great map). The link to the site is: http://www.achievementhunter.com/games/guides/brutallegend/i...
Concept Art Section:
This can be by far the most annoying part for some people, particularly when you have completed all of the other tasks and find you are only at 99%. For the complete 100%, you appear to only need to unlock to 17 concept art for Ironheade. Below is a listing of all of the concept art (8 sections in total):
1) Storyboard - 9 - unlocked by completing the game.
2) Character - 4 - unlocked by completing the game
3) Lionwhyte - 7 - unlocked by completing the game
4) Landmark - 12 - unlocked by visiting all of the vistas.
5) Creature - 9 - unlocked by killing a certain number of each creature. Note that it DOES NOT count if you kill them while you are in your car. Instead, I suggest driving around until you find the creature you're looking for, then jump out and kill them with X or LT-X (lightning attack). Rinse and repeat until each specific creatures concept art unlocks. The creatures that you need to kill are as follows: Laser Panther, Guillotar, Sickle Wraith, Metal Queen Chrome Recluse, Hextadon, Fan Leech, Raptor Elk, Tollusk, Razorfire Boar.
6) Ironheade - 17 - 7 pieces of concept art are story related. The rest are obtained by building a certain number of the each specific unit in multiplayer to unlock the specific concept art. Start a custom matchmaking game with no opponent on "Feeding Area" and put you rally point by the tentacle in the middle, then just build, sacrifice, rinse and repeat. To get the Mega Stage concept art, you need to be in multiplayer and you need to stand in the center of the maxed out Level 4 MegaStage (like a double team action) for about 5 mins. Nothing else special required. When you jump off the stage, the concept art will pop.
7) [OPTIONAL] Tainted Coil - 13 - one piece is story related, the rest art the same as detailed in Ironheade.
8) [OPTIONAL] Drowning Doom - 12 - one piece is story related, the rest art the same as detailed in Ironheade.
Side Note: Here is an estimate of the number of units needed to be built for each type (similar numbers for Drowning Doom and Tainted Coil):
- Headbangers, Razorgirls, Thunderhogs: 20-25 each
- Fire Barons, Headsplitters, Bouncer: 15-20 each
- Roadies, Metal Beasts: 10-15 each
- Rock Crushers: 4-6 each