Counterspell

Thieving Otter

Whenever this creature deals damage to an opponent, draw a card.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.