If you path Bone Curse this way, taking the left node [Iron Maiden] first and then pathing around to get to the minion application node [Merciless], the Curse will not apply to your minions. Although, if you take one point in the slowing node [Crippling Anguish] on the right to get up there instead, it works as intended and the Curse will apply to your minions. A very odd thing indeed.