I feel like Kurou will win... Even if Laharl does go nuts, Mirror of Nitocris, Atlach-Natla, and Ithaqua's homing mode are all effective ways of making it difficult for Laharl to blitz him, and he'll summon Demonbane pretty quickly if Laharl is going full power with meteors and stuff.
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"As the size of an explosion increases, the number of social situations it is incapable of solving approaches zero." -Vaarsuvius, Order of the Stick