Two sisters.

hello, colleagues, I need help. I've been playing the series since the second installment. I've practically completed all the maps on this forum. One thing is killing me: **HOW** can the first dwarf at the outpost cast "Divine Retribution" against Natalia's troops (yes, I was being a bit of a jerk and attacking his troops), if I'm wearing the "Ring of the Unrepentant" from the Necropolis set????!! O_O This breaks the entire Heroes of Might and Magic universe!!! Immunity to light, and he's using light magic!! Never mind if it were against a dark unit - that would be a racial ability with high penetration. HOW???