AugmentTower basically increases or decreases the effective range of a tower. It isn't effective at reducing damage from a tower that already does minimum damage, or for boosting the damage of towers that are already getting maximum damage on the enemy.
Stasis is one of the powers that probably will receive a nerf, yes.
All absorb does is reducing damage to a creep and turning it into energy. Is that really disruptive?
Yes, pierce is going to be disruptive. However, you can still check what parts the creep has available through getActiveBodyparts.
Barrier's barrier could just be a rampart with different properties (namely, faster decay), and blockade would leverage the same indestructible constructed walls used for novice/respawn areas.