msem-instigator

Siphon (Each -1/-1 counter you put on your creatures up to their remaining toughness while casting this pays for {1}.)
Costly Ambush deals damage equal to the greatest power among creatures you control to target creature or planeswalker.

Purge, then you may tap an untapped creature you control. If you do, purge again. (To purge, exile two cards that share a type from graveyards. If you do, draw a card.)

Equipped creature gets +2/+1.
Whenever equipped creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability.
Equip {2}

Enchant creature
Enchanted creature gets +0/+1.
Enchanted creature deals combat damage equal to its toughness rather than its power.

Move any number of +1/+1 counters from creatures you control onto target creature you control, then that creature deals damage equal to its power to target creature you don't control.

Flash
Enchant creature
Enchanted creature gets +3/+3.

Gain control of target artifact or creature until end of turn, then untap it. It gains haste until end of turn. You may spend mana as though it were mana of any type to pay the costs of its abilities this turn.

{T}: Add {G}.
Concord — {T}: Add two mana in any combination of colors. Activate only if there are four or more card types among permanents you control.

As an additional cost to cast this spell, discard a card.
Draw two cards. The next card you foretell this turn costs {0} to foretell.

{T}: Add one mana of any color.
{3}, {T}, Sacrifice Coveted Heirloom: Draw a card.
Tap three untapped artifacts you control: Return Coveted Heirloom from your graveyard to the battlefield.

Target creature can't block this turn.
Draw a card.

Target creature gets +3/+3 and gains trample until end of turn.
Reconstruct {3}{G} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

Choose two —
• Destroy target artifact.
• Discard a card, then draw a card.
• Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Wanderlust — This spell costs {2} less to cast as long as you control four or more differently named lands.
Crackle Across Kahembo deals X damage to target creature or planeswalker.

Resolute — Whenever Crackling Agama deals combat damage to a player, if Crackling Agama's power is greater than its base power, that player sacrifices an artifact or enchantment.

Enchant land
When Cradle of Civilization enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Enchanted land has “{T}: Add one mana of any color.”

Cradle of War enters tapped.
{3}, {T}: You may put an artifact card with mana value 3 or less from your hand onto the battlefield. This ability costs {1} less to activate for each other artifact you control. Activate only as a sorcery.

Equipped creature gets +2/+0 and has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Crafter's Mistake deals 1 damage to target player or planeswalker. That player or that planeswalker's controller sacrifices an artifact.

This spell costs {X} less to cast, where X is 20 minus your life total.
First strike, menace, trample

Prowess
When Cramming Student enters, conjure ten cards named Fatigue and shuffle them into your library. (They're colorless sorceries that cost {2} and have “Draw a card.”)
Instant and sorcery spells you cast cost {1} less to cast.

{2}, Exile Cranial Archive: Target player shuffles their graveyard into their library. Draw a card.

Flash
When Cranial Glass enters, exile target card from a graveyard.
{7}, {T}, Sacrifice Cranial Glass: Copy the exiled card. You may cast the copy without paying its mana cost. (A copy of a permanent spell becomes a token.)

Target creature gets +X/+0 and gains trample until end of turn.