Something I think might be involved here is the use of the small circular icons to designate certain creature properties but not others. So, momentum and plague counters have the small icons while, say, queen ability or infect ability are only listed below the card. I suppose we've all noticed that when you mutate an infected creature, it stays infected, but also when you mutate a creature with momentum, it keeps momentum. I regularly do this when my opponent has a bone or phase shield up and I create or copy a creature with momentum but it's only say 1/4 with hatch as its ability. I'll keep mutating it until I get a dragon with growth or something with high stats that will keep pounding the opponent despite the shield, and since I don't have to worry about losing momentum, I know even if I get a bad mutation there'll always be next turn.
Anyway, I imagine that's the exploit you're referring to, Forfeit,
Agreed, although if you're creative there are ways to use the current setup to your advantage.
and I wonder if this is meant to be this way or what. It seems strange to me that only momentum and infection would perform this way. I believe immortality would also remain through mutations or copies, if those creatures could be targeted...