Game Crashing during simultaneous Lissandra and Fiddlesticks ultimates - Eu West

Playing a ranked game, normal team comps. Was playing as Gnar top lane, roughly about mid game roam mid for a team fight/ pressure mid. Neither side engages directly, so poke at each other for a bit. After a while team mate zed gets ulted by enemy Lissandra as ally Fiddlesticks ults in. This simultaneous interaction strained audio and video drivers causing the game to crash and not being able to alt f4 out of it or open task manager for a soft reboot. Had to restart laptop. by the time I reconnected the game was over (our team won anyway), however got leaverbuster and low prio, with minus lp. However still got 1st win of the day bonus. Would be glad for someone to see if it just happens for me due to my crappy set up or a legit crash.