No amount of intrigue, depth or flavour can justify broken mechanics. If it was printed, Mutate would do broken things. Cards like Soulflayer are OK because they can only gain simple evergreen keywords that don't have any exploitable interactions for combos and are also crucially regulated to only every now for complexity whereas Mutate needs to fill a set. It won't work. I am not saying I don't think it will work. I am saying I am absolutely certain it wouldn't. It is too risky.
Mutate does weird things to the game, and would almost certaintly result in complexity issues, and some broken combos in at least one format. Splicing on anything except for activated abilities is dangerous and avoided by R&D intentionally for this reason. Don't use this mechanic.
(Wow, this is like the third or fourth time in the last two months I have criticised a mechanic for splicing abilities)
RUNIN: Norse mythology set (awaiting further playtesting)
FATE of ALARA: Multicolour factions (currently on hiatus)
Contibutor to the Pyrulea community set
I'm here to tell you that all your set mechanics are bad
#Defundthepolice
(Wow, this is like the third or fourth time in the last two months I have criticised a mechanic for splicing abilities)
RUNIN: Norse mythology set (awaiting further playtesting)
FATE of ALARA: Multicolour factions (currently on hiatus)
Contibutor to the Pyrulea community set
I'm here to tell you that all your set mechanics are bad
#Defundthepolice