Zamorak soldier superpower

It seems some of Zamorak’s soldiers have superpowers. Today I was hunting them down, when there is one that I simply cannot kill. I usually take down one in 3-4 hits, but this one refused to even take damage! Even with ultimate abilities I do nothing… there is nothing appearing on top of the soldier, not even a 0. Eventually I died… Combat 200 with 91 range and death lotus+ zaryte died to a zamorak sniper… GF?

After that, I saw a Zamorak Warlock who doesn’t die. I hit him 2 times and it went down to 0 hp…. But it kept fighting! WTF? After it went to 0 hp I couldn’t attack him anymore, but I am still getting attacked by him. When I try to use abilities my characters does not move. He won’t even retaliate, with auto-retaliate on.So eventually I died again…

Is it me or is that a tad bit unfair?