Glub, the Mana Dart

Evolve, Graft 0
{x}{g/u}{g/u},{t}: Put X +1/+1 counters on Glub, the Mana Dart or Move X +1/+1 counters from Glub, the Mana Dart to target creature.
Remove a +1/+1 counter from Glub, the Mana Dart: Add one mana of any color to your mana pool.
How can something so tiny have so much energy and vitality?