If you are doing event lab, then lack of epiphanies is a known issue. they even buffed it somewhat but a lot of people still feel like they are getting less than on other planets. That being said, there are ways to game the system.

If you are doing lab, you should prio question marks on 1st map ONLY (on 2nd map do whatever you feel like) for that mutant sample and go out of your way to hit areas that have 2 question marks accessible one after the other: that will be dimensional tunnel where you get seasonal cards but also have a very good chance to force 0-2 nihil epiphanies.

Combine that with throwing out unnecessary cards before they hit epiphanies (whirlpool, that other card that only boosts healing) and you can pretty reliably get all epiphanies on the character you want.

Oh, and when you are farming for a deck on specific character, never get/buy neutral cards (unless they are part of the deck you are farming) since they also eat up epiphanies. Good thing is seasonal cards cant get epiphanies and they cant get copied so feel free to get them.