msem-instigator

Counter target spell with no subtypes. Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

When Coralight Champion enters, create a white Aura enchantment token named Hila's Favor attached to target creature. The token has enchant creature and “Enchanted creature has double strike as long as there's another Aura attached to it. Otherwise, it has first strike.”

Whenever Uncanny Allocator enters or attacks, give any number of permanents and/or players with counters on them another counter of each kind already there.

Sacrifice a creature: Harrowing Knight gets +2/+2 until end of turn.

When Seishin Tidekeeper enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have flying.

Equipped creature has hexproof.
Whenever equipped creature dies, draw a card.
Equip {2}

Marinton Occultist can't block or be blocked.
Whenever one or more cards are put into a player's graveyard from their library, Marinton Occultist gets +1/+1 until end of turn.

Equipped creature gets +2/+0 and has deathtouch.
Equip Rogue or Assassin {1}
Equip {3}

Menace
Whenever Masoh enters or attacks, each opponent that has more than four cards in hand discards cards equal to the difference. Then if you have fewer than four cards in hand, draw cards equal to the difference.

Enchant creature
Enchanted creature gets +2/+0 and has first strike.
Mirage {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 a creature an opponent controls becomes blocked, put a -1/-1 counter on that creature.

Enchant creature
Enchanted creature gets +2/+2.
When enchanted creature dies, amass Soldiers 2. (Put two +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)

{1}{G}: Rhudai Pathfinder gets +X/+X until end of turn, where X is the number of differently named lands you control. Activate only once each turn.

Equipped creature gets +2/+2 and has trample.
Equip {2}

You may cast Gateblessed Explorer from your graveyard as long as you control three or more creatures.
Whenever another creature dies, each opponent loses 1 life and you gain 1 life.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Mausoleum Revenant deals damage to a player, create a 2/2 black Zombie creature token.

When Null Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Whenever you cast a sorcery spell, each opponent loses 1 life and you gain 1 life.

Whenever a creature you control dies, Oakpoint gets +4/+0 until end of turn.

Creature tokens you control get +1/+1 and have distorted. (They can be blocked by tapped creatures but not untapped creatures.)

Whenever equipped creature deals combat damage to a player, draw a card.
Whenever a Vehicle you control becomes a creature, you may attach Planar Uplink to it.
Equip {U}

{T}: Add {U}, {B}, or {R}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Put a +1/+1 counter on target creature. It gains hexproof until end of turn.

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Hapless Chronomancer dies, if it had no time counters on it, return target instant or sorcery card from your graveyard to your hand.

Trample
When Arpechian Bellowers enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Search your library for a green creature card, reveal it, put it into your hand, then shuffle.

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature gets +1/+1 for each enchantment you control and has first strike.