Let's Go Gambling!

At the beginning of your upkeep, roll a d20.
1 | Prevent all damage that would be dealt by
sources you control until your next turn.
2-5 | All damage is halved, rounded down, until
your next turn.
6-10 | This card has no effect.
11-15 | All damage is doubled until your next turn.
16-19 | All damage is tripled until your next turn.
20 | Damage dealt by sources you control is
tripled until your next turn.
"Aw dang it"