Empower Jace won't let you put loyalty counters on nontoken Jace planeswalkers. However, if you control a Jace planeswalker token that you got another way (such as an effect that creates a token that's a copy of a permanent), empower Jace will put loyalty counters on that.

If a planeswalker you control has zero loyalty counters while you control Sanctum Lurker, it will not be put into its owner's graveyard. You may still activate abilities of that planeswalker that cost [0] or that add counters to it as a cost, such as the one granted by Sanctum Lurker.

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.

Only one loyalty ability of each planeswalker may be activated per turn, no matter how many it has gained.

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.

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.