Eh, what? Constantine's 'no name' spells are, more often than not, exceedingly effective on 'big name' opponents--just ask Phantom Stranger, Spectre, Zauriel, Swamp Thing, etc. etc. etc. On that note, is Ymir capable of cross-dimensional teleportation under his own power? I do not recall him ever doing so, but perhaps a 'Ymir-bag'(hyuck-hyuck) out there might know of such an instance.
Assuming he cannot teleport, what is stopping John from BFR'ing him to another dimension like he did to Dark Orko/Skeletor?