Gollum, Riddle Master (Borderless)

'As Gollum enters, choose odd or even. (Zero is even.)
Whenever an opponent casts a spell with mana value of the chosen quality, choose one that hasn't been chosen —
• Put a +1/+1 counter on Gollum.
• Each opponent loses 2 life and you gain 2 life.
• Draw a card.