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.
A player, 27 January 2014
The ability on Ring of Earth isn't absent (or home, for that matter), so I have a couple of questions.
1) If someone uses an effect like Coward! to bring my personality into a battlefield in which I have no units, can I discard ring of earth to negate the movement?
2) If A movement effect like Block Supply Lines moves my last personality from a battle, can I discard ring of earth to negate the movement?
3) Which card types need to have Home to be used in a battle in which the card is not present? (I'm assuming holdings and rings, but are there any more exceptions?)
A player, 27 January 2014
1) No
2) Yes. At that point you still have Presence because the action hasn't resolved yet, so you can play Interrupts
3) Cards in units need the Home keyword. That means Personalities, Followers, Items and Spells. All other card types (Holdings, Rings, Strongholds, Events, Sensei, Strategies, etc.) need not because they are usually not in locations (Terrains and Kata are notable exceptions though).