Anti-cheat toggler and offline launcher is a simple tool that is not a workaround for the EasyAnti-cheat. It will not help you play online with a modded client. This tool is not a solution for the EasyAnti-cheat and will not help you play online with a modified client. It's meant for easily switching between a modded and non-modded play. It is safe to use as it will not cause any issues even if you turn it on after you turn it off. 

How safe is this?

This tool is completely safe. The anti-cheat gets completely turned off and won't punish you for it even if you turn it back on. However, I cannot guarantee that the anti-cheat will not detect modified saves (infinite runes, overpowered gear, etc.) if you decide to re-enable the anti-cheat afterwards.