These are what I think of as the "primary strategies" for the bosses. All of these can be killed in other ways, but these are the main things I'm thinking about.
NB I'm not actually that good at the game. Some of this is regurgitated from people who are better than me, some are my own thoughts, all errors are mine.
Damage race. You need to be able to do a lot of damage, very quickly. It is very unlikely that you can scale your block well enough by that point to survive the second big hit, so you need to kill it first.
Being able to consistently put out a little block while you do that is also extra good - an orichalcum is great here - but you might just have to block with your face in this fight.
The big things you're trying to do in this fight are:
- Split the big slime in three turns before it crushes you.
- Do Area of Effect damage once the slime is split (or just reliably split them further)
Big thwacky cards that you can reliably draw early are good here. Also if you're on Ironclad anything that interacts with statuses is good here. I love Evolve in general, but it's an extra great pick for Slime Boss. Firebreathing is extremely pickable here in a way that it usually isn't, because it turns those slimes into the AoE you need.
Consistent block/damage balance. You need to be able to block basically every turn, or this fight will be sad. Normally in Act 1 you don't want to be picking up too many block cards, guardian changes that.
Also the first split is often the hardest and you want to split before it does a lot of damage, and certainly before it piles debuffs on you, so it's really helpful to have a good turn one damage card. Backstab is great for guardian, as is bag of marbles.
This tests your ability to set up. Champ is pretty chill until you get him below half health, and then he gets super aggro, so you want to have some cards that you can play early and will set you up for doing a billion damage when you're ready. Catalyst, demon form, etc. are good. A cultist potion will often solve this fight for you. Frost orb or other block strategies which mean champ can't hurt you easily when he gets mean also work.
I don't really have a set of things I think about with collector. I probably should, but I both haven't really got the hang of this fight and don't find it too hard.
Ability to kill the minions reliably is important though - both because you want to kill them, and because collector will waste a turn resummoning - so AoE is important here.
Main things to think about here:
- If you rely on debuffing the enemy, being able to reliably strip artifact charges is important.
- You will be down some possibly-critical cards, so you need to either be able to kill the minions to get them back, or you need to be able to do without them. Sometimes doing without them is good! It makes your deck smaller. Often you can go infinite in this fight even if you can't do so in other fights.
- Hyperbeam will hurt. You need to either be able to survive it (e.g. buffer, intangible, a billion block), or you need to be able to kill it before the hyperbeam hits you.
This is a test of how fast your deck scales.
Important questions:
- Can you deal several hundred damage before their strength gain overwhelms you?
- Can you deal with a deck full of dazes?
Strategies for this include:
- Status combos or lots of draw
- Deal many damage real quick
In particular the question you should be asking is how slowly your deck scales. If it's slowly, you're going to have a bad time in this fight. Pick accelerators - things that get you cards and energy early on.
If your deck is power heavy, try to pick up a dark shackles or piercing wail so you can strength down before killing the first phase (the strength loss is made permanent if you apply it on the turn it dies)
In general the thing with awakened one is just be good at both blocking and dealing damage. You can control how much it scales by controlling how many powers you play, or you can just outscale it.
The main thing with time eater is to be sure that if you card spam (e.g. with shivs) you can consistently play 12 cards every turn. Ideally you want to be able to win this fight without card spam.
Things that scale you without playing cards (e.g. orbs, noxious fumes, demon form, cultist potion) help a lot here.
Remember that time eater doesn't scale unless you play cards.
Card draw is very useful in this fight, because time eater will fill your deck with slime and also give you a card draw down debuff.