Why were elemental instabilities removed? I remember hating these fully as a low level player, and in the attacker-is-invincible-and-does-auto-crits-not-protected-by-armour era to boot. However, they were one of the cooler concepts elementalists had by my account. Maybe they seemed more in the realm of the Chaotic-Lord, but I think with some fine-tuning elemental instabilities could come back. Maybe as low level uncontrolable pets that do low level crits until they explode, some random time later?
