Wrathful staff

It's half of what it would do with Wrathful. If a staff unit without Wrathful does 10 damage to a unit, with Wrathful they would do 20.

Staff Unit has 50 Attack vs Defending Unit with 30 Resistance:

Under normal units, the damage output would be 20, but because it's a Staff unit damage is halved and turned into 10. Putting on Wrathful Staff negates this effect and damage is back to 20.

Healers normally deal 50% of dmg, like if they have 40atk and attack someone with 20res they will deal 10dmg because 50% of 40-20 is 10, while with Wrathfull staff the dmg will be 20