So im leveling my second warlock and noticed that when you cast seduction with your Succubus its supposed to break on damage, but still im able to cast 1 (damaging) spell without it breaking, im not sure where besides duel you could have a need for it this works without the mob being in combat, being in combat and it can have taken damage before doing this.
Also note it seems you HAVE to have your spell land within the first few seconds of when the seduction hits, so start casting when you make your pet seduct, nothing that requires good timing
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TL;DR, cast seduction while while casting spell, let it hit after seduction, seduction wont break