Secret Ingredient is too powerful. With spell damage/debuff immunity already in place there are some ways to make a completely invincible nether or almost invincible normal creatures:
Secret Ingredient is one of the “stats do not matter”-traits from Siralim 1. Ironically Slib’s trait from Siralim 1 was fine since you could replicated its effect with pill
If you want to keep the current version, at least secret ingredient should provide healing immunity. Otherwise here are some simple nether/two creature combos that provide invincibility:
- Nether Imler with Patch up/Secret Ingredient -> enemy does damage, damage is healed
- Twin Valkyrie -> two Valkyrie Shieldmaiden next to each other with Secret Ingredient artifact (not completely invincible due to artifact decay)
These are only the attack trigger healing effects. If you can reduce the number of attacks to below 5/turn (cough Nostalgia cough) you can get away with healing on your turn.
There are probably more ways to break the game with Secret Ingredient but at least recovering health should not be an option
Personally I would change it to something that keep the spirit from the Siralim 1 trait (something like “Every x battles increase this creature’s gene strength by 1”).