Remember this is also TARGETING. If it mutates it still freezes the creature targeting it. Also, it doesn't have to survive an attack to freeze/congeal the targeter/hitter.
You're going to need to combo it with another card before it can do anything. So lets say you put a rage elixer on it. That costs you 2 cards, 5
and 3
, and it only does 6 per turn.
It's just not efficient enough. Compare it to some other 2-card combos:
2* Deadly Poison ( 2 cards + 4
, only countered by purify)
2* Immortal (2 unupped cards + 12
for 8 damage that can't be targeted at all)
Abyssal Crawler + Quintessence (2 cards + 4
3
, can't be targeted at all)
And if you don't draw the rage elixir, or you have to use the rage elixir for creature control, then Floe does nothing at all.
Even if you do get the combo out, I can still stop it in all the usual ways: rewind, many shields, antimatter, even eternity and owl's eye. Even if I do target it with one of my creatures, I still messed up 2 of your cards and only messed up 1 of mine; and its my choice; if I'd rather eat the 6/turn and save my squid for your dragons, I can.