msem-instigator

As a spell you control is countered by a spell or ability an opponent controls while you control a Mountain, you may reveal Confront the Riddlemaster from your hand. When you do, cast it without paying its mana cost.
This spell can't be countered.
Confront the Riddlemaster deals 4 damage to any target.

Conjure Quicksand deals 1 damage to each creature and planeswalker you don't control and each battle you don't protect.

Exile target creature you control, then return it to the battlefield under its owner's control. Create a token that's a copy of it. Those creatures gain haste until end of turn. Sacrifice the token at the beginning of the next end step.

As an additional cost to cast this spell, discard a card.
Draw two cards. Add one mana of any color.

Consuming Flame deals 6 damage to target creature.
Ferocious — If you control a creature with power 4 or greater, the damage can't be prevented and that creature can't be regenerated this turn.

Enchant creature
Enchanted creature gets +2/+1 and has “Whenever this creature attacks, target creature an opponent controls can't block this turn.”

Destroy target land. Continental Collapse deals 2 damage to that land's controller.

Controlled Burn deals 2 damage to target player or planeswalker.
At the beginning of your upkeep, you may exile Controlled Burn from your graveyard. If you do, it deals 2 damage to target player or planeswalker.

For each nonland permanent you control, you may create a token that's a copy of it. If it's a creature, it gains haste. Exile all tokens created this way at the beginning of the next end step.

Destroy target artifact. Create two 1/1 colorless Servo artifact creature tokens.

Enchant opponent
Whenever enchanted opponent casts a spell, you may reveal cards from the top of your library until you reveal a nonland card that costs less. Exile that card, and put the rest on the bottom in a random order. You may play the exiled card until the end of your next turn.

Core Ignition deals X damage to target creature or planeswalker.
Conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Cosmic Catastrophe deals 6 damage to target creature or planeswalker. If you control a creature with power greater than its base power, Cosmic Catastrophe deals 3 damage to each opponent.

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.

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

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.

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

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

Creatures you control gain trample until end of turn.
Draw a card.

Crater Burst deals 3 damage to any target. Add {W}{U}{B}{R}{G}. Until end of turn, you don't lose this mana as steps and phases end.

As an additional cost to cast this spell, discard a nonland card.
Draw two cards.

Whenever you cast a spell for an alternate cost, create two 1/1 red Elemental creature tokens. (This includes “without paying its mana cost.”)
Whenever you cast a red spell from your hand, reveal the top card of your library. If that card has a lesser mana value, you may cast it without paying its mana cost. Otherwise, draw a card, then discard a card.

Create three 2/2 red Noble creature tokens with disgraced 1. (Each enters with a -1/-1 counter. Whenever one deals combat damage to a player, remove all -1/-1 counters from it.)