The idea of a "permanent" creature is a good one, but the stats are way to OP.
A burrowed Antlion is a 3
creature with 2/4 stats (and you need to wait 1 turn).
This enchanted with a PA is a 6/7 creature for 4
in one turn, for 2 cards.
This is still OP.
I'd suggest to reduce Attack and HP, and make it immune to abilities and spells that work on creatures, like lobotomise, freeze, congeal, lightning, fire blast etc. But is still effected by shields. (I'm not sure if this is possible with the current game code).