Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Sisay, Weatherlight Captain

Sisay, Weatherlight Captain gets +1/+1 for each color among other legendary permanents you control.
{W}{U}{B}{R}{G}: Search your library for a legendary permanent card with mana value less than Sisay's power, put that card onto the battlefield, then shuffle.

Dig Through Time

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Mage's Guile

Target creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
Cycling {U} ({U}, Discard this card: Draw a card.)

Treasured Find

Return target card from your graveyard to your hand. Exile Treasured Find.

Counterspell

Demonic Tutor

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

Archaeomancer

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.