Witch's Cauldron

When a creature you control dies, put a number
of Brew counters on Witch's Cauldron equal to
its mana cost. Double it if it is a frog or newt.
{t}: Remove XX Brew counters from Witch's
Cauldron, add X to your mana pool. This mana
may be counted as any color when casting an
Enchantment spell. This mana may not be used
to cast creature spells.
"Bubble Bubble toil and trouble; Fire burn, (ribbit)
cauldron bubble." - Shakespeare.