Angrath sticks out to me among the planeswalkers as having a pretty unique angle. His +1 is a solid group slug ability that makes it difficult for your opponents to keep cards in their hands. This pairs nicely with having one-shot wincons while your opponents are guaranteed to be answer-free. His -3 is a great ability to combine with sac outlets, which also has some cross synergy with treasure, which also has some cross synergy with the whole big-wincon thing in the form of revel in riches and big X spells. Having a clear board is of course great for a planeswalker's survival, and it's also great if you're doing a steal + sac strategy, as weenies generally aren't worth it so it's better to clear them out en mass with sweepers.
So there's a lot of cross synergy going on here between stealing, sacking, sweeping, treasure, discard, big wincons. It's built to be a relatively high-curve deck that's not looking to play much to the board until the later turns with some big bombs and grinding down of enemy resources with the commander and other tools.