msem-instigator

{T}: Add {G}.
{G}, {T}: Target creature gains trample until end of turn.

Whenever another nontoken creature enters the battlefield under your control, create a 1/1 green Saproling creature token.
{1}{G}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

{U}: Aqueous Treader gets +1/-1 until end of turn.
{U}: Aqueous Treader gets -1/+1 until end of turn.

Flying
When Arbiter of Silence enters the battlefield, exile all other creatures until Arbiter of Silence leaves the battlefield. (They return to the battlefield under their owners' control.)

Enchant creature
Enchanted creature gets +1/+1 and has flying and prowess.

{U}, Exile an instant or sorcery card from your graveyard: Draw a card, then discard a card.
{R}, Exile an instant or sorcery card from your graveyard: Arcane Harvesters deals 1 damage to any target.

Whenever you cast an instant or sorcery spell, you may pay {1}. If you do, choose one—
• Draw a card, then discard a card.
• Tap target creature.
• Target creature gains flying until end of turn.
• Target player mills two cards.

Counter target spell. If that spell is countered this way, until the end of your next turn the next spell you cast that shares a type with it costs {X} less to cast, where X is the countered spell's mana value.

Counter target spell unless its controller pays {2}.
Reprise {3}{U} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

When Arcanomancer enters the battlefield, return up to one target instant card and up to one target sorcery card from your graveyard to your hand.

When Archaeomancer enters the battlefield, return target instant or sorcery card from your graveyard to your hand.

Kicker {1}{R} (You may pay an additional {1}{R} as you cast this spell.)
Attacking creatures get +2/+0 until end of turn. Those creatures also gain first strike until end of turn if this spell was kicked.

Target creature gains double strike until end of turn.

Enchant creature (Target a creature as you cast this. This card enters the battlefield attached to that creature.)
Enchanted creature gets +2/+2.
{1}{G}: Regenerate enchanted creature.

Arsenal Curator gets +1/+1 as long as you control a Plains.
{2}{W}: Untap target creature you control. It gets +0/+1 until end of turn.

Exile up to two target permanents you control, then return those cards to the battlefield under your control.

Counter target spell unless its controller pays {1}. If you control an artifact, instead counter that spell unless its controller pays {4}.

At the beginning of each upkeep, if an opponent controls more creatures than you, create a 1/1 colorless Thopter artifact creature token with flying.

Target player sacrifices an attacking creature.
Bulwark — That player sacrifices two attacking creatures instead if you control a creature with toughness 4 or greater.

Vanishing 4 (This permanent enters the battlefield with four time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Equipped creature gets +3/+3.
Equip {2}

When Auramancer enters the battlefield, you may return target enchantment card from your graveyard to your hand.

Kicker {U} (You may pay an additional {U} as you cast this spell.)
Flying
If Aven Ranger was kicked, it enters the battlefield with a +1/+1 counter on it.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever a nontoken creature enters the battlefield under your control, you may pay {1}{W}. If you do, create a 1/1 white Bird creature token with flying.

Engorge (As this enters the battlefield, mill three cards, then exile a card from among the milled cards.)
When Bane of Sanity enters the battlefield, if it engorged a creature card, target player discards two cards.