Hello.

Maby it seems obvious, but I have some doubts.

"At the end of your battlefield phase, deal 1 dame to each of your opponent's units that could have defend but did not."

Does it work only if malus participated in attack or it works whenever player who controls malus attack ?

(for example malus is on / kingdom zone)

Best regards

Mich

Where is (KZ,QZ,BZ) Malus do not matter for the effect of the card. (there is no zone requirement on the card)

So if I have malus on kingdom and attack with another units malus effect anyway works, right ?

Yip. You got it. Much like the Bloodthirster, whose text states that damage cannot be cancelled, Malus does NOT have to be the one attacking for his constant effect to apply. Think of the cards that say things like, "When this card leaves play, (something something happens)." Malus doesn't mention himself, so his effect is constant.