Inperfect Sage Mode

Cumulative upkeep: {c}
Enchant creature
Enchanted creature has +X/+X where is the
amount of {c} in your mana pool times two
rounded down, If this creature would
be damaged or targeted instead roll a d20.
1-5 | Prevent all effects (including damage)
that would be dealt to this creature.
6-20 | All effects (including damage)
are applied like normal.