Welcome to the comunity. You mean on pvp, you try to avoid a fight by swimming and your chaser killed your thrall. Because in pve there is not a way to loose your thrall, except vertical elevators and lava. So if you don’t want your thrall to be killed this way, all you have to do is go out to the sore and walk a little until you’ll see your thrall following you and go back to the water. This way you will confuse your chaser and you will both escape safely .