msem-instigator

Reverberate {2}{G} (When you cast this spell, copy it if you paid its reverberate cost. The copy becomes a permanent when it resolves.)
Mystical Echo gets +1/+1 for each other Reflection you control.
Whenever you discard a card, Reflections you control gain trample until end of turn.

Trample
Skalnir, Ruinbringer enters with X +1/+1 counters on it.
When Skalnir, Ruinbringer enters, it deals damage equal to the number of +1/+1 counters on it to each creature without trample.

{T}: Add {C}.
{2}, {T}: Add {C} for each Desert you control.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Winding Snake has three or more +1/+1 counters on it, remove them all and transform it.

Flying, vigilance
At the beginning of your upkeep, if you control four or more Plains, put a +1/+1 counter on each other creature you control.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Scry 1.
[Lore III] Target creature you control can't be blocked until end of turn.

When Improvisionist enters, if it was the second spell you cast this turn, exile the top card of your library. You may play that card until the end of your next turn.

Equipped creature has vigilance and “{T}: Add one mana of any color.”
Equip {1}

Whenever you make first contact, Runic Enforcer gains lifelink until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Exile target nonland permanent an opponent controls. If this spell was harnessed by a token, you gain 5 life.

As Mind-Mute enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.
{5}: Return Mind-Mute to its owner's hand.

Moonlit Shore enters tapped unless you control two or more blue and/or black permanents.
{T}: Add {U} or {B}.

Whenever Orria Mirrorpelt becomes the target of a spell, exile that spell. If Orria Mirrorpelt was its only target, copy it for each other creature target player controls. Each copy targets a different one of those creatures.

Whenever you sacrifice a Clue, Vivian's Vanguard gets +2/+0 and gains flying until end of turn.

Advance {1}{R} (Cast this for {1}{R} to advance it as it enters. {1}{R}: Advance this as a sorcery.)
Whenever Blitz Breaker advances, its power becomes equal to the amount of noncombat damage that's been dealt to your opponents this turn. (This effect lasts indefinitely.)

If an opponent controls more lands than you, search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.

Draw two cards, then discard two cards. Then if you cast Price of Wisdom from your graveyard, create a 3/3 blue Sphinx creature token with flying.
Flashback {4}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Flying, trample
Nether Fiend enters with a lifelink counter on it.
{B}{B}, Pay 6 life, Remove a lifelink counter from Nether Fiend: Draw six cards.

Choose one —
• Target creature you control gets +0/+2 and gains hexproof until end of turn.
• Return target nonland permanent to its owner's hand.

Deathtouch

Look at the top two cards of your library. Put one of them into your hand and the rest into your graveyard.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Return two target creature cards from your graveyard to the battlefield. Shuffle Tearful Reunion into its owner's library.

Target creature you control fights target creature you don't control.

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
{T}: Add one mana of any color.
{T}: Add X mana of any one color, where X is the greatest number of counters among creatures you control.