Polathur, Wielder of Worlds

Changeling, split second
Polathur, Wielder of Worlds has all activated abilities of other Shapeshifter and Spellshaper creatures you control.
{w}{u}{b}{r}{g}: Choose one -
• Discard an instant or sorcery card. If you do,
cast a copy of it.
• Polathur becomes a copy of target creature until
your next turn.