Aura of Abjure

Whenever the first card in a turn enters the exile
zone, put an Aura counter on Aura of Abjure.
Return Aura of Abjure to its owner's hand: Add
an amount of blue mana equal to the number of
Aura counters on this card. If this mana is used
to cast a spell without Abjure, Aura of Abjure
deals an amount of damage to you equal to that
spell's converted mana cost.
{u}{u}{u}, Discard Aura of Abjure: Draw a card.