Sharn, Guileful Rogue

When Sharn, Guileful Rogue attacks, she gain's
+2/+3 and you flip a coin. if you succeed, you
may select an opponents target creature to block,
then roll a D20.
0-9 - No effect.
10-18 - Gain Double Strike.
19-20 - Sharn finds the creature's back, gaining deathtouch, Indestructable, Double Strike and
doubles her power.