So I like to use Guardian Kay'est in duels but when its the only monster on my field it can't be a target, so instead of my opponent ending their turn they attack me directly when Guardian is still on the field. I dont understand how they can pass my guard.
That's how the card works. The game is using the old wording so I can see how people can get confused by it. The new errata makes the effect much more clear.


Cannot be Summoned unless you control a face-up "Rod of Silence - Kay'est". This card is unaffected by Spell effects and cannot be targeted for attacks, but does not prevent your opponent from attacking you directly.