Perceive your Non-existence

(You may only cast a legendary instant if you control
a legendary creature or planeswalker.) Roll a d20.
1-10: Until your opponents cast 8 spells, you skip
your draw step, your life total can't change, you
can't vote, you can't cast spells or activate
abilities, and your creatures, planeswalkers and enchantments phase out.
11-20: Until your next turn, you can't lose life,
your permanents gain indestructible, and
creatures you control gain +5/+5 and flying.