- Go to Control Panel>Appearance And Personalization>Make text or other items smaller or Larger>Set to "Smaller - 100%"
- Right click HoN > Properties > Compatibility > Make sure Disable display scaling on high DPI settings is UNTICKED
- Try changing your ingame resolution
Go back to the GeForce website and download the latest drivers for your card. Then uninstall your video card software and reinstall with the downloaded one (preferably in safe mode)
Well, I suggested a reinstall of the driver just in case that there was something corrupted, as 99% of the time it is a driver issue (usually out-of-date though).
Should it not work, can you specify when the cursor issue began (date/HoN patch/major software installation/hardware changes/...)?