3W Creature Human Cleric
When Arena Rector dies, you may exile it. If you do, search your library for a planeswalker card, put it onto the battlefield, then shuffle your library.
This is clearly not as game-ending as Academy Rector, but it also doesn't need a build-around deck.
The feeling I have about him is that it's in the same position BKelly Oath decks are to Griselbrand/Emrakul ones: you're playing less powerful cards, but castable ones. With Academy Rector you're playing Omniscience and Bargain, which mostly only come down on the table with Rector himself. With this you're playing an assortment of already playable PWs, but maybe you can shove that Nicol Bolas or Old Karn or Ugin in there too.