Aura's auto deactivated

Hmm... I have a thought on this for possible consideration.

High level golem spells can take a lot of mana to cast. It almost sounds to me as though the game wants the player to have enough unreserved mana to cast the spell, even when triggering it (in the case of the manual cast problem, I'm assuming there's at least a minor reduction in mana cost coming from somewhere, and the game is calculating at the full value). This leads to the following two situations.

Type 1 of the bug: Toon has 1000 mana, no aura passives and no enlighten, nothing otherwise modifying reserve cost, and 50% + 35% reserved (call it whatever you like, Haste+Discipline for example). This leaves 150 mana open. The carrion golem would cost 180 mana to cast, but cannot be manually cast because it is on a trigger. The trigger goes off, and the game detects insufficient mana for the spell, and unreserves at random one of the auras to compensate.

Type 2 of the bug: Toon has 1000 mana, no reserve modifications or supports on the aura, and 50% reserved, thus 500 open. Carrion golem is linked with a pile of support and costs 470 to cast, but the toon also has 12% reduced mana cost of skills from passives. The player casts the golem. The system detects a mana cost of 534 (the base cost before the reduction), and unreserves the aura.

What's odd is why it would be doing this sort of behavior with Carrion Golem specifically. I've never seen any other skill cause this.

Edit for a minor math error.