msem-instigator

{T}: Add {C}.
{3}{B}: Until end of turn, Tzhai's Throne becomes a 2/2 creature. It's still a land. It gets +2/+2 if {R} was spent to activate this ability, gets +2/+2 if {G} was spent, and gets +2/+2 if {W} was spent.

Vision (Whenever this or another creature enters the battlefield under your control, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Ulek Crusher envisions a creature card, it gets +2/+2 until end of turn.

When Ulek Elder enters the battlefield, look at the top card of your library. You may put it into your graveyard.

This spell costs {1} less to cast for each Scarecrow you control.
Other creatures you control get +0/+2 and have vigilance.

Vision (Whenever this or another creature enters the battlefield under your control, reveal the top card of your library. Then you may put that card into your graveyard.)
As Ulek Wayfinder envisions a land card, you may put that card onto the battlefield tapped.

Vision (Whenever this or another creature enters the battlefield under your control, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Ulek Windrider envisions an instant or sorcery card, it gets +1/+0 and gains flying until end of turn.

Flash
If a card or token would be put into an opponent's graveyard from anywhere, exile it instead.

Destroy target artifact or enchantment. You gain life equal to its mana value.

This spell costs {2} less to cast if you control a Scout.
Search your library for up to two basic land cards, reveal those cards, and put one onto the battlefield tapped and the other into your hand, then shuffle.

Whenever a creature you control is dealt damage, put a +1/+1 counter on that creature.

When Uncovered Idol enters the battlefield, scry 1.
{1}, Sacrifice Uncovered Idol: Put a +1/+1 counter on target creature. Activate only as a sorcery.

When Uncovered Mine enters the battlefield and at the beginning of your upkeep, return a random card from your graveyard to your hand.

You may have Undecided Mimic enter the battlefield or phase in as a copy of any creature on the battlefield, except it has this ability and “{2}{U}{U}: Undecided Mimic phases out.” (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Undercity Diplomat can't be blocked by marked creatures.

{T}, Sacrifice a permanent: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

At the beginning of your upkeep, reveal the top card of your library. If it has the same name as a card in your graveyard, put the revealed card into your hand. Otherwise, put it into your graveyard.

Undine Coven gets +1/+1 for each other Merfolk you control.
Whenever you cast a noncreature spell, Undine Coven deals 1 damage to target player or planeswalker.

Archive 0 (As this enters the battlefield, shuffle the top zero cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
As Undue's Study enters the battlefield, shuffle your graveyard into the archived library.

[+2]: Exile up to three target cards from graveyards.
[+1]: Create a 2/1 black Horse Zombie creature token with lifelink.
[0]: If Undue has six or more loyalty counters on him, each opponent returns a creature card of their choice from a graveyard to the battlefield under your control.

Target creature you control explores. Then it fights up to one target creature you don't control. If that creature has flying, the creature you control deals damage equal to its power to it instead. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on that creature, then you may mill that card.)

Menace
{3}{B}, Discard a card: Unhallowed Singers gets +3/+0 until end of turn. Whenever it deals combat damage to a player this turn, they discard a card.

Starting with you, each player may sacrifice a creature. Each player that doesn't loses life equal to the total power of creatures sacrificed this way.

Whenever you cast an enchantment spell, reveal the top card of your library. If it's an enchantment card, you may put it onto the battlefield.

Exile the top five cards of your library. Until end of turn, you may play any number of cards exiled this way with mana value less than or equal to the number of colors among permanents you controlled as you cast United Fervor.

Create X 1/1 white Nymph creature tokens. Until end of turn, creatures you control gain protection from each color among permanents you controlled as you cast United Force.