In the later maps of Kaycee's Mod, the biggest killer is deck size. With all challenges enabled, you'll encounter combinations which can wipe you in a single turn, like Wolves with Double Strike or Bifurcation totems. And it only takes a few superfluous cards to give you an unplayable starting hand.

Unfortunately, there's very little that you can do to mitigate this. So you really need to prioritise the few things you can control about deck size.

Maps are generated in a way such that you have a choice of paths, but all paths will add/subtract the same number of cards. However, this balancing doesn't account for some events being failable. Some events can be failed to great success, some other events have alternative behaviours to ensure you accidentally get screwed over.

Your choice of items. Under normal circumstances, Backpacks will not award a card.

However, Backpacks will give a Pack Rat if have a full set of items. This is usually avoidable though — try to look ahead in maps before starting battles to see if you'll need to burn an item.

Bone Altars consume a card, and then you'll get an extra bone at the start of each map (or 4 if you sacrificed a Black Goat). Not much to say here. There's no trick to these.

You draw a card, from a) three random cards, b) your choice of cost, c) your choice of tribe. Unfortunately these are generated in parallel with each other on maps, so you can't avoid taking a card.

Campfires allow you to increase the power or health of your cards. You can gamble to get twice the increase.

However, when you gamble you will sometimes lose the card. For this reason, it's worth considering not murdering the Campers with Ring Worm/Touch of Death in the first map. Risk-free double power increases are extremely enticing but, in my experience, you rarely need more than 6 power on any card, and only on a few cards.

Unfortunately, while there is a mechanism to ensure success at campfires, there is no mechanism to ensure failure. You might be able to shed your excess cards, or you might accidentally give them huge power/health. When picking cards to feed to the campers, consider what your options are if the card survives.

Deck Trials will offer a selection of cards with extra sigils already imbued if you can pass your choice of trial. However, you can fail Deck Trials and avoid taking a card.

These are the trials you can be offered:

• Trial of Bones: 3 cards cost at least 5 Bones
  
• Trial of Blood: 3 cards cost at least 4 Blood
  
• Trial of Power: 3 cards have at least 4 Power
  
• Trial of Health: 3 cards have at least 6 Health
  
• Trial of Wisdom: 3 cards have at least 3 Sigils
  
• Trial of Tribe: 2 cards have matching tribe

The way to mitigate this is to try and cultivate certain weaknesses in your deck in order to fail trials more consistently. Personally, I try to limit the number of bone cards in my deck. But your deck may have generally low health or low blood or mismatched tribes, and you should try to keep it that way when picking new cards.

Duplicate your card of choice from any in your deck, complete with sigils (although some details may be randomised).

This always results in an extra card but is generally worth it if you have something cool (like a card you've powered up to kill Grizzlies).

Merge two duplicates. Under normal circumstances, Mycologists will consume a card.

However, if you have no duplicates you will be forced to take one. The duplicates offered will be of three random cards in your deck. You can try to use this effect to your favour (it's always nice to draw another Geck) but it's usually not worth pushing your luck (you'll probably wind up duplicating trash).

The way to mitigate this is, obviously, to try to draw duplicates ahead of time. It's just a factor to keep in mind when weighing the relative value of cards when you're forced to pick one.

Sacrifice one card to imbue its sigils onto another. Under normal circumstances, Mysterious Stones will consume a card.

However, if you don't have two suitable cards the stones will have no effect. This situation is unlikely to occur when you have a large deck, but it's something to be mindful of.

Pick a boulder and you'll get either a Golden Pelt or a random insect with a random sigil. Either way, it's another card.

Trade your pelts for cards. It's a 1-1 trade but you need to get pelts in the first place.

Trade teeth for pelts or a Skinning Knife. You will always draw a Rabbit Pelt. You can trade for more, but I would recommend against it (except maybe a Golden Pelt if you're feeling lucky).

Your choice of totem pieces. No cards here.