In general, in my opinion, Raven is an absolute anti-hero against strong machine heroes like Viti, Deleb, and he also fights well against Dwarves, Razazak, and Shaka. That is, Deleb has no chance from the start. Raven should play defensively, hide skeletons and princes behind ghosts and large creatures, and destroy as many devils as possible on the first turn, then machines, and then proceed according to the situation.
In general, try playing with Domovoi; Albolabris is strong, of course, but it's still better to play with the original. He will show how to defeat Ossir and Axel with Letos, and vice versa.