The ensnare idea sounds promising. I don't know if it ought to be on a flesh spider though.
A more "natural fit" would be putting a trapping function on the antlion since that's what antlions actually do in real life. Burrowing in this game is purely defensive, but the real antlion uses it's pit to pull in unsuspecting ants that wander too close. (Like the sarlacc at the Great Pit of Carkoon in Return of the Jedi.)
And yes, I realize the antlion already has burrow ability, but how many times have you ever run into an antlion in a match? And when you do burrow it only does 1 damage which pretty much removes any usefulness it would have if up against a shield. And since
already has the shrieker, why have 2 creatures with the same ability and have one of them suck?
So, not to "hijack" the ensnare idea too much, but I think it would be a better fit for the antlion. The flesh spider needs a retooling too--maybe a vampire-like ability but it could bite opposing creatures (like siphon life) for some
cost thus making it a true "flesh" creature.