Not really a bug, nor a suggestion, just bringing attention to an issue.
Screen resolution might have a massive impact in PvP type issues. I play on a huge desktop monitor (2560x1600 but I think 1900x1024 is the highest supported ingame resolution).
That means I can target and cast offensive spells on skeletons etc that are much farther off than someone with a smaller resolution. So in a PvP battle, a mage playing at high resolution can target and kill players who cannot even see him onscreen if they are on a mobile device with lower resolution.
In PvE it's probably no big deal. Just something to keep in mind, I am not sure how to "fix" or balance this. It might just mean that custom worlds that are heavily PvP oriented, want to keep that in mind