A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
viewtopic.php?f=59&t=58102
Is it legal to bring a card into play (rather than Create a card) in a battle with No Units?
Is it legal to bring a personality into play in the battle if you control no units at the current battle regardless of whether or not the Enemy does?
The only thing that seems to waive Presence (besides card text) is movement, correct?
http://www.alderac.com/forum/viewtopic.php?f=59&t=58102
Is it legal to bring a card into play (rather than Create a card) in a battle with No Units?
Is it legal to bring a personality into play in the battle if you control no units at the current battle regardless of whether or not the Enemy does?
The only thing that seems to waive Presence (besides card text) is movement, correct?
No, no, correct.