In Guardian Legend, the second or third tentacle eyeball is more than evil. He is some kind of omnipotent turbo monster. He's lays down field after field of those green rods that kill you in two hits. He's just not fair. Second hardest boss is Velius from FFT, at least if Velius is the four-armed goat man with the demon coharts. Because of him I'm stuck on my second run through the game.
Yes, I've tried using summoners with Lich, but he's clever enough to kill them on the first turn.