Trinisphere

As long as Trinisphere is untapped, each spell that would cost less than three mana to cast costs three mana to cast. (Additional mana in the cost may be paid with any color of mana or colorless mana. For example, a spell that would cost {1}{B} to cast costs {2}{B} to cast instead.)

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Aether Barrier

Whenever a player casts a creature spell, that player sacrifices a permanent unless they pay {1}.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Sol Ring

Arcane Laboratory

Each player can't cast more than one spell each turn.

Soul Barrier

Whenever an opponent casts a creature spell, Soul Barrier deals 2 damage to that player unless they pay {2}.

God-Pharaoh's Statue

Spells your opponents cast cost {2} more to cast.
At the beginning of your end step, each opponent loses 1 life.