Eternal Witness

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

Abandoned Sarcophagus

You may cast spells that have a cycling ability from your graveyard.
If a card that has a cycling ability would be put into your graveyard from anywhere and it wasn't cycled, exile it instead.

Panharmonicon

If an artifact or creature entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Dockside Extortionist

When Dockside Extortionist enters the battlefield, create X Treasure tokens, where X is the number of artifacts and enchantments your opponents control. (Treasure tokens are artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Fluctuator

Cycling abilities you activate cost up to {2} less to activate.

Shadow of the Grave

Return to your hand all cards in your graveyard that you cycled or discarded this turn.

Kenrith, the Returned King

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.

Anger

Haste
As long as Anger is in your graveyard and you control a Mountain, creatures you control have haste.

Kydele, Chosen of Kruphix

{T}: Add {C} for each card you've drawn this turn.
Partner (You can have two commanders if both have partner.)

Archaeomancer

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

Songs of the Damned

Add {B} for each creature card in your graveyard.

Escape Protocol

Whenever you cycle a card, you may pay {1}. When you do, exile target artifact or creature you control, then return it to the battlefield under its owner's control.

Torment of Hailfire

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card.