Sibling Rivalry

{x}{t}If you take damage from a source controlled
by a Sibling other than Sibling Rivalry, you may
pay X mana, where X equals the damage dealt,
and deal X damage to that Sibling.
{2}{u/r}{u/r}{u/r} Put a copy of Sibling Rivalry
into play under target player's control.
All players that control Sibling Rivalry are
Siblings.