Game Mechanics: Players being invincible after zoning?

[Lazortag]

Recently we were attacking a monk from another guild who had just zoned out, and we nuked him maybe 10 times without any damage being done. We got spells-landed messages for each nuke which I believe rules out the possibility of a DA idol being used but I could be wrong. This also happened over a period of around 30 seconds so again, I doubt he was invincible by any legitimate means. Of course it could have been unintentional but still this is a pretty serious bug.