Zhumix, Conjurer Savant

Companion — Your starting deck contains only
white and blue cards, and land cards.
(If this card is your chosen companion, you may
cast it once from outside the game.)
When you cast your first white spell each turn,
exile target creature an opponent controls with converted mana cost 3 or less.
When you cast your first blue spell each turn,
create an enchantment token with "Whenever
target opponent casts a spell, counter it, then
sacrifice this token."