I found a bug in the Sigil of Power skill

Normally, stacking layers for Sigil of Power requires consuming mana while inside its area of effect. Skills supported by Lifetap cannot consume mana, and therefore cannot stack layers for Sigil of Power.

However, when Pyromantic Pact is allocated, skills that normally consume mana cannot stack layers (which is expected), but skills supported by Lifetap paradoxically gain the ability to stack layers.