Rashmi, Eternities Crafter

Whenever you cast your first spell each turn, reveal the top card of your library. You may cast it without paying its mana cost if it's a spell with lesser mana value. If you don't cast it, put it into your hand.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Unwind

Counter target noncreature spell. Untap up to three lands.

Counterbalance

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, counter that spell if it has the same mana value as the revealed card.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Voidslime

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Counterspell

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Insidious Will

Choose one —
• Counter target spell.
• You may choose new targets for target spell.
• Copy target instant or sorcery spell. You may choose new targets for the copy.

Dream Fracture

Counter target spell. Its controller draws a card.
Draw a card.

Quandrix Apprentice

Magecraft — Whenever you cast or copy an instant or sorcery spell, look at the top three cards of your library. You may reveal a land card from among them and put that card into your hand. Put the rest on the bottom of your library in any order.

Disallow

Rewind

Counter target spell. Untap up to four lands.

Delay

Counter target spell. If the spell is countered this way, exile it with three time counters on it instead of putting it into its owner's graveyard. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Plasm Capture

Counter target spell. At the beginning of your next first main phase, add X mana in any combination of colors, where X is that spell's mana value.