Please restrict Titan-Egi and Topaz Carbuncle summoning unless the Tank currently is disconnected or has been voted out of the duty or left voluntarily. Some Arcanists will summon Topaz Carbuncle to tank bosses and thus the tank will not be able to generate enough enmity to take back from Topaz.

Either do this, or increase enmity generation by all tanks considerably. (Via passive or otherwise.)