Oleron's might and war cry

Is 20% Reduced target’s damage from Oleron’s Might stacking with 25% reduced target’s damage from war cry ?
Thx for answer.

Nope. War cry will just override Might’s debuff

This. The stronger will take effect; so Oleron’s Might is worthwhile if you have an underleveled War Cry, but otherwise WC is applicable when maxed.