Helena Adams, The Mind's Eye

Haste
{t}: Put one Decode Counter on Helena
Adams, the Mind's Eye.
{t}: Remove all Decode Counters from Helena Adams, the Mind's Eye. Add {u} to your mana pool for each Decode Counter removed in this
way.
When a creature you control blocks an opponent's creature, you may untap Helena Adams, The
Mind's Eye at the end of that combat phase.