msem-instigator

Enchant player
Whenever enchanted player becomes the target of a spell or ability they don't control, if it isn't a copy, its controller copies it.

Hexproof
When Overburdened Trader enters, create three 1/1 colorless Construct artifact creature tokens.

Counter target spell. For each other card named Overcharge in your graveyard, create a colorless Canister artifact token with “{T}, Sacrifice this artifact: Add {C}.”

Whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy. Overclock deals X damage to you, where X is the number of spells you've cast this turn.

Kicker—Sacrifice an artifact or creature. (You may sacrifice an artifact or creature in addition to any other costs as you cast this spell.)
Choose target creature you control. Put a +1/+1 counter on it if this spell was kicked. Then it deals damage equal to its power to target creature you don't control.

Destroy target creature with power 4 or greater. (You need a target to cast this spell.)
Tap up to two target creatures.

When Overconfident Batter dies, if it's enchanted or you cast a spell that targeted it this turn, you gain 3 life.

Until end of turn, creatures you control have base power X/Y, where X is the greatest base power among creatures you control and Y is the greatest base toughness among creatures you control.
If you control a creature with flying, creatures you control gain flying until end of turn. The same is true for first strike, haste, lifelink, menace, prowess, trample, and vigilance.

Any number of target players each draw seven cards, then discard seven cards.

Target creature gets +2/+1 and gains haste until end of turn.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Target player reveals their hand. You choose a nonland card from it. That player discards that card unless they discard three other cards.

{G}, Tap an untapped Nymph you control: Overgrown Beast gets +2/+2 until end of turn.

Overgrown Siren must be blocked if able.

Trample
Overgrown Spellroot gets +1/+1 for each creature token you control.
When Overgrown Spellroot enters, create four 1/1 black Worm creature tokens.

When Overgrowth Guardian enters, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Whenever Overgrowth Host attacks, germinate. Then creatures you control that are Saprolings or have counters on them gain trample until end of turn.
Saprolings you control get +1/+1.

This spell can't be countered.
Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Haste (This creature can attack and {T} as soon as it comes under your control.)

Each player discards two cards. Then if there are four or more card types among cards in your graveyard, create two 1/1 white Human creature tokens.

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.)
Overheat deals X damage to any target.

Overkill deals 4 damage to any target that was dealt damage this turn.

Creatures you control get +3/+3 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever you sacrifice a permanent, Overseer of Armies deals 1 damage to each opponent and each battle they protect.

At the beginning of each upkeep, create X 1/1 white Soldier creature tokens, where X is two plus the number of creatures you control.

Recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)
Target creature you control fights target creature you don't control.

Creatures you control get +3/+3 until end of turn and creatures your opponents control block this turn if able.