Way of the Mentor

If more than one creature you control with lifelink deals combat damage at the same time, the last ability will trigger once for each of those creatures.

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.

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.