[gerdalti6980]

Is there a way to make it not attack mobs tagged by other players?

I second this, skipping tagged mobs would be a great improvement. I did browse through the DEV data and could not find a good indicator for that.
Only the HP of the mob could be used but one would need to poll the HP while casting and abort if necessary.

I actually commented out this bit of code right at the very end, and it stops that behavior.

Code:

        local el = EntityList("nearest,alive,attackable,onmesh,fateid="..tostring(fateID))
        if ( el ) then
            local i,e = next(el)
            if (i~=nil and e~=nil) then
                return e
            end
        end