If this tower has at least 20 mana when it attacks, it will pay all its mana to proc a critical strike. 20 Mana is used to grant the critical strike and every further point of mana spent grants 9% more critical damage to that attack.
Level Bonus: -.25 Mana needed
Spellfire
This tower treats all spell modifiers as attack bonuses, with an 90% bonus gain of stated effect.