LoL not responding in task manager/crashing

It's been happening for quite a while now, and I'm getting tired of having to open up task manager to close LoL, which ends up losing the game for me. Happens a lot on ARAM, at random moments, and it has happened 3 times in a game so far.

very rarely when a crash happens/I try to reconnect, a box pops up saying a Direct X error has occurred. Please help me, it's ruining league for me and makes me want to quit :( I have DirectX12 if that helps.

I've updated my Nvidia 1080ti graphics card, updated my windows 10 to the latest version, checked for updates for windows 10, I've done client repair in the past many times, which kept the crashes at bay for a while but they returned, tried loads of other things but still nothing.