Input the following seed into the Community Challenges section.
Start with the Cultivating champion for the +1 card draw and grab the Improved Firebox artifact.
Turn on the trial for the first fight and pick up the Siren of the Sea monster. Take the left path for the gold and to decrease one of your Frozen Lances to 0 cost.
Early game strategy is to put the Siren behind your champion and cast as many spells as possible to pump her.
Grab Restoration Detonation from the second fight and head left again to add 10 magic power to it at the Merchant of Magic. You can give the guy in the ice cave a unit just to keep it out of your deck for a few fights.
Definitely get the Lodestone Totem after defeating Daedalus. This is probably the most OP card in the game. Go with the capacity upgrade so everyone outside your conductors can fit on one row and switch to the Explosive champion upgrade now that your champion will no longer be taking any significant damage.
I would head right after this fight to start thinning down your deck. Don't blow all your gold just yet as you'll want to buy an artifact later on.
If you are going for maximum points you can turn on the trial for the level 4 fight which gives a useful artifact, you can also take the Restoration Retreat to ensure you always have your units on the bottom floor even when they won't fit but it is not necessary for the build.
Take the right path on level 5 and reroll the Merchant of Steel to add multistrike to your Siren.
On level 6 use the Unstable Vortex to thin out your conductors.
After you beat the boss Archus, upgrade your card draw. Take the left path to grab the Forever Flame from the random trinket box and then Winged Steel from the shop.
Turn on the trial for the level 7 fight to get that sweet 400 gold which you'll use to thin out cards before the final boss.
Take the left path and put another multistrike on your Siren then purge any remaining non-healing cards you can using the Vortex and merchant. Ideally you should have about 7-8 spells left.
Boss strategy is pretty straightforward. Place everyone on the same floor and cast spells like crazy. You'll need to put everyone on the second floor because they will not fit on the first. If going for points, you can decend the Edge Prior using the Restoring Retreat to get everyone on the first floor.
This can unlock the Win at Covenant 5, 10, 15 and 25 achievements if you do not have them already as well as The Awoken.