Shards of Mastered Fortuity

Cleave {3}{u/r}{u/r} (You may cast this spell for its cleave
cost. If you do, remove the words in square brackets.)
Roll a d20. Discard two cards [at random] then—
1 | Draw a card.
2—9 | Draw two cards.
10—19 | Draw three cards.
20 | Draw three cards. Add {u} or {r} for each
time you've discarded one or more cards this
turn. [Until your next turn,] you don't lose this
mana as steps and phases end.