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.

( can be paid with either or 2 life.)
, , Sacrifice a creature: Search your library for a creature card with converted mana cost equal to 1 plus the sacrificed creature's converted mana cost, put that card onto the battlefield, then shuffle your library. Activate this ability only any time you could cast a sorcery.

Search your library for a card, put that card into your hand, then shuffle your library.

Search your library for an artifact or enchantment card and reveal that card. Shuffle your library, then put the card on top of it.

Colorless Eldrazi spells you cast cost less to cast.
, : Search your library for a colorless creature card, reveal it, and put it into your hand. Then shuffle your library.

Search your library for a card, put that card into your hand, discard a card at random, then shuffle your library.

Reveal a card from your hand. Search your library for a card with the same name as that card, reveal it, put it into your hand, then shuffle your library.
Hellbent — If you have no cards in hand, instead search your library for a card, put it into your hand, then shuffle your library.

When Spellseeker enters the battlefield, you may search your library for an instant or sorcery card with converted mana cost 2 or less, reveal it, put it into your hand, then shuffle your library.

Other enchantments you control have shroud. (They can't be the targets of spells or abilities.)
, Sacrifice Sterling Grove: Search your library for an enchantment card and reveal that card. Shuffle your library, then put the card on top of it.

Search your library for a creature card and reveal that card. Shuffle your library, then put the card on top of it.