If youre looking to really amp up your power in the late game, i've found that working with mutagens is super important. The trick is to match those colored skills with the right mutagens like putting red combat abilities next to red mutagens, that kind of thing. Its actually pretty cool how much stronger you get when you line everything up properly.

Something that really changed the game for me was grabbing that synergy skill in the alchemy tree. You need about 20 points to get there, but trust me its worth it since it boosts all your mutagen effects by half. I usually start by focusing on greater mutagens too, since you can make them by combining three regular ones together.

If you've got the expansion installed, theres this really powerful mutation called euphoria that just takes everything to the next level. Works amazing with high toxicity builds, and speaking of toxicity, dont forget about mixing in some decoctions to keep those bonuses running.

The way i usually do it is pick a focus first like if you want more sign power go with blue mutagens, or if youre all about that sword damage stick with red ones. Green ones are pretty solid too if youre having trouble staying alive, but personally, i tend to lean towards the red ones since the damage boost is just so good.

One thing that took me a while to figure out, but works really well, is keeping an eye on your toxicity levels with some good alchemy skills. Delayed recovery is pretty sweet for making your buffs last longer, and it all works together really nicely with the whole mutagen setup.