Hey there. I don´t understand a description info.

Tunic of Zubei
MP Recovery Rate -5%

Does it debuff your character ? so 5% worse mp recovery ?

That is correct, if you have a 50 mp per 5 seconds regeneration rate for example, after equipping Zubei set you're gonna have 48.5 mp per 5 seconds regeneration rate. It only affects your innate MP regen, it doesn't affect mana received from rechargers, kookaburras, other mp regen buffs, etc.

That set gives 10% magic attack though, so it's not a bad choice at later chronicles where casting speed doesn't affect your skills reuse. I would stick to Avadon on chronicles like Interlude.