Baffled by new Baron

First post ever, but finally found something worth sharing. No pics or video to my knowledge sadly, though I'd love it if there were. Definitely lol'd.

Normal 5v5, Braum support, went 2/2/17.

Assisted Yi and Varus in getting fed, was helping Xin get to that point. We attempted to close out with simultaneous Baron and base run. Varus, Liss and Yi at their base, Xin and I at Baron. I W'd to Xin at Baron upon arriving and suddenly, died instantly (literally). I was full health (3000+) and plenty of armor (not great vs Baron, but figured health-wise I was fine). What is this new Baron and what did he do to me. I feel violated. Either this was a glitch, or Baron was hiding how bm he actually is on the old rift. Still won the game though.

True Story.