Any effects that last "until your next turn" or similar won't expire just because they'll go through an additional beginning phase
Vengeant has 3 great abilities that make him very capable of defending himself, gaining card advantage and/or tempo and posing as a scary game ending threat that needs dealing with
Starting with these partner pairs is the tip of an immense iceberg
I love it in ramp to win the game and make your other big stuff trample, madness, discard matters, Golgari self-mill, Jund's Lord Windgrace lands return to the battlefield from the graveyard, Sultai's self-milling Sidisi, Brood Tyrant, blink, midrange, tokens, and loads more
If you have a Cube or Commander collection these will definitely stand out among them