I mean in a war between the Dwarves and the Slann the Slann could just win by, well, doing what they did last time twice, shift the continents one way out of alignment and another way back into alignment, there'd be twice the catastrophic earthquakes and the Karaz Ankor has to undergo the Time of Woes 2: Geomantic Boogaloo.
Oh the dwarfs would certainly die, but I'm not sure the Lizardmen would win. You can't really kill throngs with earthquakes and enough armies with nothing to lose can kill Slann, we know that because Skaven killed several. I think the only ultimate victor would be Chaos, but just being able to rationally acknowledged that fact and not start a war with the frogs who caused the single most destructive event in the history of the Karaz Ankor shows wisdom.