msem-instigator

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Create a tapped colorless Mountain Forest land token. (It has “{T}: Add {R} or {G}.”)

Discard a card: Tender Warden gets +2/+2 until end of turn. Activate only during your turn.

Look at the top eight cards of your library. You may reveal up to one Elf and up to one Dwarf card from among them. Put the revealed cards into your hand and the rest on the bottom of your library in a random order. Tenuous Alliance deals 2 damage to you.

Attacking creatures you control have trample.
Whenever a creature you control attacks, you may remove any number of +1/+1 counters from that creature. If you do, it gets +2/+2 until end of turn for each counter removed this way.

Vigilance, trample
When Threshold Guardian enters, return a creature you control to its owner's hand.

Vigilance, menace, trample, haste
Whenever you cast a spell, you may have Thunderous Avarice consume. If you do, put a +1/+1 counter on it. (To consume, sacrifice another creature or exile a creature card from your graveyard.)
Whenever an opponent casts a spell, they may have Thunderous Avarice consume. If they don't, put a +1/+1 counter on it.

Whenever a creature you control enters, Timid Thunderhorn gets +X/+X until end of turn, where X is that creature's power.

Enchant creature
Enchanted creature gets +3/+3 and has trample.

Whenever another nontoken creature you control enters, that creature gains haste until end of turn. Then Tremor Seer deals 1 damage to any target.

I — Create a 1/1 red Hound creature token.
II — Create a 4/4 green Rhino Warrior creature token with trample.
III — You may have two target creatures you control fight. If you do and exactly one survives, put four +1/+1 counters on that creature.

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
{4}{R}{G}: Twinblade Paragon gains double strike until end of turn.

Flying
When Tyrant of Tributes enters, target opponent sacrifices X permanents, where X is half the number of permanents they control, rounded up. You gain X life.

Whenever a land becomes tapped, its controller sacrifices it and creates a Treasure token.

Trample
Whenever this creature enters or transforms into Valseid, Leyran Brute, it deals 2 damage to any target that isn't a blocking creature and you gain 2 life.
{3}{R}{G}: Transform Valseid, Leyran Brute. Activate only if it's attacking.

Trample
Whenever this creature transforms into Valseid, Leyran Ravager or you cast a Wolf or Werewolf spell, Valseid, Leyran Ravager deals 2 damage to any target that isn't a blocking creature and you gain 2 life.
At the beginning of your end step, if Valseid didn't attack this turn, transform it.

Create a token that's a copy of target creature or land you control, except it has haste and “At the beginning of the end step, exile this permanent.” If a land you control was targeted this way, create two of those tokens instead.

Reach
Wanderlust — Voliv Skyhunter gets +2/+0 and has first strike as long as you control four or more differently named lands.

You may exert Wiedfree Berserker as it attacks. When you do, target creature can't block this turn. (An exerted creature won't untap during your next untap step.)
If exerting a creature you control causes a triggered ability of a permanent you control to trigger, that ability triggers another time.

Whenever a player casts an instant or sorcery spell, Wiedfree Roughrider deals 2 damage to that player.
Whenever Wiedfree Roughrider attacks, you may pay {X}. When you do, destroy target noncreature, nonland permanent with mana value X.

At the beginning of combat on your turn, if you control a creature with power 4 or greater, put a +1/+1 counter on Wilderkin Zealot.
{R}{G}: Target creature gains trample until end of turn.

{2}{R/G}: Wildershrine Warden gets +2/+2 until end of turn. You may have it assign its combat damage this turn as though it weren't blocked. Activate only once each turn.

Wildfire Elemental has frenzy 4 as long as you control no other creatures. (Whenever this creature attacks and isn't blocked, it gets +4/+0 until end of turn.)
Wildfire Elemental has frenzy 4 as long as you have no cards in hand.

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
You may cast the top card of the archived library. Whenever you do, copy that spell. You may choose new targets for the copy.

[+1]: Add {R} or {G}. You can't spend this mana to cast an Elf spell.
[–2]: Winona, the Heretic deals 4 damage to any target. If that target is an Elf, Winona deals 4 damage to that Elf's controller.
[–6]: Until end of turn, any time you could cast an instant, you may pay {R}. When you do, Winona deals 2 damage to any target.

Target creature gains haste and trample until end of turn.
Fabled {3}{R/G}{R/G} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)