Hi, welcome back!
A few things have changed within Tibia I would recommend looking them up! But a few things and mainly, is the dove mode! You can't attack others using an area spell anymore if you're in green dove mode. Yellow dove mode is for more or less attacking yellow skulls, or white skulled characters. Red is where you can get skulled for blocking, shooting magic walls or casting area spells just like the old PVP system. It's more or less helped botters bot further and quicker using UE, Avalanches and GFB's. But I guess you have to play it, experience it and go through it to understand it.
Regards,
BnW.