Musashi and his T3 are literally just another Beast Warlord+Lantern situation

[GrimDusk]

I am currently fighting a defense team in arena against a musashi with his T3 and labs, and he is attacking infinitely. Can anyone possibly explain why you would make a character immune to negative effects and give him the ability to attack for eternity?

Edit: this has been going on for at least 10 minutes now. This has to be a bug, right? Surely this isn't intentional.

Edit 2: It has officially run out the arena timer, but Musashi is still attacking. You cannot even draw against this.