Talk:Manus, Father of the Abyss/@comment-4511886-20131126203501/@comment-1379800-20131127003924

Nope, bosses only gain HP if you summon before the fight.

If you begin a summon, and then immediately enter the boss room before the phantom is actually summoned, the boss will not have the HP boost.

This is easy to do with Solaire against the Gargoyles.