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.

Exchange control of target creature you control and target noncreature spell an opponent controls. You may choose new targets for that spell.

As an additional cost to cast this spell, tap an untapped Warlock you control.
Search your library for a card and put it into your hand or graveyard, then shuffle.

Target opponent chooses a card type, then reveals their hand. You choose a card from it that's not of the chosen type. That player discards that card.

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.)

Draw two cards. Each opponent loses 2 life and you gain 2 life.
Flashback {4}{U}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

For any number of target spells or abilities your opponents control, counter it unless its controller pays {4}.

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.

Counter target spell.
Surveil 1.

Reveal the top five cards of your library. For each card type, you may put a card of that type revealed this way into your hand. Put the rest into your graveyard. Then you may cast a nonland card with mana value 3 or less from your hand without paying its mana cost.

Enchant creature
Enchanted creature gets +2/+2 and has “Whenever this creature attacks, tap target creature defending player controls.”

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.

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.

As Coveted Tower enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {G}, {U}, or {R}.

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.)

Enchant creature or planeswalker
Enchanted permanent can't attack or block and loses all abilities.

You mill two cards, draw two cards, lose 2 life, and create two Treasure tokens. (They're artifacts with “{T}: Sacrifice this permanent: Add one mana of any color.”)

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.”)

Choose two —
• Create a 6/6 blue Kraken creature token.
• Take an extra turn after this one.
• End the turn.
Exile Crack in Time.

This spell has flash as long as you control a permanent with flash.
Put target nonland permanent on top of its owner's library.