where is dark contract, unbreakable resolve and how you ether get galatea or endbringer?
"Galatea, Endbringer" is the full name of a single card--you receive it at the start of a new run, after you win and see the credits.
Dark Contract is from the Base Set, at Epic rarity (10DP, max 2 per deck)
Unbreakable Resolve is a common, I think? It's in the Succubus set. It gives Regen 2, Max HP Boost 2, and Max MP Boost 1, so if you can't find it, Mana Geode from the Base Set is also fine--it gives MP Boost but not the other effects. I went with Unbreakable Resolve because I was starting the fight missing a bunch of HP already, and that didn't fly with me.