Well I told him I'd tell you, so I'm filling my end of the bargain. [ he grumbles, a bit under his breath. Strange...just isn't going to mention all those slightly dubious bits of the talk that RM's probably filing away under 'reasons why Strange shouldn't talk to Ignatius' (aka that whole heart business.) ]

If I had to make a guess on why he wants to go, I think he wants the mirror as a bargaining chip for himself.