Fist of Suns

You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Sauron, Lord of the Rings

When you cast this spell, amass Orcs 5, mill five cards, then return a creature card from your graveyard to the battlefield.
Trample
Whenever a commander an opponent controls dies, the Ring tempts you.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Jodah, Archmage Eternal

Flying
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Sol Ring

Patchwork Banner

As Patchwork Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{T}: Add one mana of any color.

Soul of Emancipation

When Soul of Emancipation enters, destroy up to three other target nonland permanents. For each of those permanents, its controller creates a 3/3 white Angel creature token with flying.

Primeval Spawn

If Primeval Spawn would enter and it wasn't cast or no mana was spent to cast it, exile it instead.
Vigilance, trample, lifelink
When Primeval Spawn leaves the battlefield, exile the top ten cards of your library. You may cast any number of spells with total mana value 10 or less from among them without paying their mana costs.

Progenitus

Protection from everything
If Progenitus would be put into a graveyard from anywhere, reveal Progenitus and shuffle it into its owner's library instead.

Leyline of Mutation

If Leyline of Mutation is in your opening hand, you may begin the game with it on the battlefield.
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.