Spellmaw Wurm

Defender, reach
Spellmaw Wurm can block up to three extra creatures with flying each combat.
Whenever an opponent casts an instant or sorcery spell that costs three or less, put two +1/+1 counters on Spellmaw Wurm.
{2}{g/w}{g/w}: Put a +1/+1 counter on Spellmaw
Wurm.