Hmm, to start, try running the Hextech Repair Tool to make sure it is installed correctly, and that your settings are all right. You can also force a repatch, which since this problem started with the recent patch would certainly be worth trying.
If that doesn't work, try updating your graphics drivers and see if that helps:
#HOW TO IDENTIFY YOUR GRAPHICS CARD
- Press [Windows Key] + R (this will open up a "Run" window).
- Type dxdiag and then hit Enter.
- Select the Display tab.
- Note the name and manufacturer of your card in the top left corner of the window.
Most common graphics card manufacturers have a solution that scans your computer and updates drivers automatically. They can be found here:
AMD
NVIDIA
Intel
And visit the Microsoft DirectX page here to make sure DirectX is up-to-date and installed correctly.
It may also be worth resetting your graphics software to default, in case there is some setting that is throwing league off:
- Right-click on your desktop and select NVIDIA Control Panel.
- Select Manage 3D Settings.
- Click on Restore Defaults.
#CATALYST CONTROL CENTER
- Right-click on your desktop and select Catalyst Control Center (also called VISION center).
- Select Preferences.
- Click on Restore Factory Defaults.
If none of the above solutions help, Riot Support has a handy Troubleshooting Guide that goes over this sort of problem and possible solutions.