One thing I think is worth mentioning is that his mystery can damage friendly units.

First unit i've encountered, i think, that can do this.

If you have not selected a unit when triggering his mystery, or if line up his mystery to trigger after your pos 1, and your pos 1 ends up killing ibikis target, ibiki will instead decide he cant continue to live with not getting the spotlight and will choose to commit seppuku by using his mystery on himself.

This happened to me in a few laggy matches in arena, so i went to the kakashi clones to test something out and ibiki can indeed use his mystery on himself or to attack one of your own characters.