Tralosk speaks the truth. Exactly as much morale will be removed as can be applied. The rest will remain.

Why full? Advanced resistance is already above 50%. And expert resistance exceeds 70%. I'm not counting cloaks, as they may not be present. But if they are, then it's even higher.

Now, tell me, would you risk wasting a turn with a powerful Haven mage, trying to cast hypnosis/berserk on a unit with resistance above 50%? I wouldn't. It's better to focus on creation: teleport or something else. Or berserk on those same ifrits.