Theorist's Proxy

If you control a Jace planeswalker token, you can't choose to create a new one when you empower Jace. You have to put the loyalty counters on your existing Jace planeswalker token. In the rare case that you control multiple Jace planeswalker tokens, you'll choose one of those tokens to put the loyalty counters on.

To empower Jace N, if you don't control a Jace planeswalker token, create a blue Jace planeswalker token with 0 loyalty, "[−1]: Surveil 1," and "[−3]: Draw a card." Choose a Jace planeswalker token you control. Put N loyalty counters on it.

Some spells and abilities that empower Jace may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve. You won't empower Jace.