How near-immortal Sorcerers die

Immortality or near-immortality can make characters sound quite invincible. If they heal fast or never get sick, how can anyone ever kill them? They sound much too powerful and you know what? I don't like invincible characters or beings that are all powerful and no one can EVER kill them off. That just sounds too convenient to have characters like that. It's like flawless characters. That's my personal opinion 😛 So what do I do? I come up with a way for Sorcerers to die.