Silmaril

Indestructible, if it or attached creature is removed
from battlefield return to void.
Grants Feanor or Finglofin +15/+15 if equipped.
Grants any other creature +10/+10 if equipped.
{5} attach to target creature player controls.
{5} detach from target creature. Does not detach
until beginning of the players next upset. If not
attached to new creature within 1 turn it is cast
back into the void.
{1} If in void, roll a D20 die. If it's a 3, target
creature you control may now possess it.