Can Janna be played to base at reaction speed, and will her ability work there?

Changed due to errata of triggered ability 'up to one unit'

Janna can be played to base at reaction speed (anywhere you could play a unit whenever you can play reactions), and her ability will trigger because of an errata. Her new card text is: 'When you play me, heal your units here, then move up to one enemy unit from here to its base.' Up to one can be zero. So there is no need to target an enemy unit with the 'when you play me' trigger and that way the heal effect can still happen for your units in base.