msem-instigator

When Spreading Dissent enters, exile all creatures until Spreading Dissent leaves the battlefield.
{X}: Put a random creature card with mana value X exiled with Spreading Dissent onto the battlefield. Any player may activate this ability.

Enchant creature
Enchanted creature gets +2/+2 and has flying.
When enchanted creature dies, draw a card.

Target opponent sacrifices a creature. Create an X/X black Zombie creature token, where X is the sacrificed creature's power.

[+1]: Choose up to one target creature. Until your next turn, whenever that creature attacks you or Kimar, Kimar deals 4 damage to that creature.
[–1]: Put a +1/+1 counter on target creature. That creature gains lifelink until end of turn.
[–7]: Search your library for a creature card and put it onto the battlefield. You gain life equal to its power. Then shuffle.

Whenever a creature or planeswalker enters, its controller may have it deal damage equal to its power or loyalty to any target of that player's choice.

Prowess
When Scarlands Singularity enters, each player conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

{R}, {T}: Put a luster counter on Awestone.
{1}{R}, {T}: Add {R} for each luster counter on Awestone.
{2}{R}, {T}: Until end of turn, gain control of target nonland permanent with mana value less than or equal to the number of luster counters on Awestone and it gains haste. Untap that permanent. Activate only during your turn.

Create a 1/1 blue Bird creature token with flying. (Cast a copy of this spell once while this creature is on the battlefield.)

Return target spell to its owner's hand. If there are three or more colors among permanents you control, you may counter that spell instead.

Enchant creature
Enchanted creature gets -1/-1 and can't block.
Enchanted creature gets an additional -1/-1 for each card named Garrote in your graveyard.

Enchant creature or planeswalker
Enchanted permanent has base power 0 and loses all abilities.

When Forserval enters, creatures you control get +1/+1 and gain haste until end of turn.

At the beginning of your end step, choose any number of permanents and/or players, then give each another counter of each kind it already has.
[+1]: Scry 1. Add {U} or {R}.
[–X]: Exile the top X cards of your library. Until end of turn, you may play a card exiled with Trainee Karina Oblay.

{T}, Mill a card: Add {B} or {G}.
Once each turn, when a creature you control dies or a creature card is put into your graveyard from anywhere other than the battlefield, each opponent loses 1 life.

When Thoughtgrinder enters, each player discards a card.
Unearth {1}{U}{B} ({1}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

{3}, {T}: Tap target creature.

Sacrifice Scrapyard Raiders: Target artifact gains indestructible until end of turn.

Haste
Sandstorm Sentinel enters with X +1/+1 counters on it, where X is your fealty to Deserts. (Each Desert you control counts toward your fealty to Deserts.)
Mirage {1}{R} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Whenever you cast a spell, Wandering Precursor gets +1/+0 until end of turn for each color of mana spent to cast that spell.

Lifelink
Whenever one or more other creatures with power 2 or less you control enter, you gain 1 life. If your life total is greater than your starting life total, draw a card instead. This ability triggers only once each turn.

You may choose not to untap Glacial Shelf during your untap step.
{T}: Add {C}.
{4}, {T}: Tap target creature that's attacking you. It doesn't untap during its controller's untap step for as long as Glacial Shelf remains tapped.

Counter target noncreature spell unless its controller pays {1}. If there are four or more counters among creatures you control, counter that spell instead.

As an additional cost to cast this spell, exile two cards from your graveyard with the same mana value.
Search your library for a card with the same mana value as the exiled cards, reveal it, put it into your hand, then shuffle.

Whenever a Wizard you control deals damage to a player, draw a card.