Abomination's purple passive power (Gamma Toxins) says, in part, "Reduces enemy match damage by 20% and ... Gamma Mutates' match damage by an additional 30%." However, he is also reducing ally match damage.
As a test case, I made a match in the 4* essential node of the third sub in The Hunt using 5* Gambit. My Gambit's match damage for red is 2422, so a red match-3 should do 7266 damage. However, it actually did only 5086 damage. (This is 70% of what the damage should be.)
So not only is this power penalizing your own team, but it's reducing it by 30% (which is, curiously, neither the 20% enemy reduction nor the 50% Gamma Mutate reduction).
Edit: An alliance mate first identified this issue. In his case, he was using Shang-Chi and Valkyrie. He calculated that his first match should have generated 4609 damage, but it was only 3918 (which is, oddly, a 15% reduction).