What does the "100% upgrade scroll" do?

[KillU]

Is it literally 100% chance to upgrade, even to like +10? O.o

[Adi]

Up to 7 only.

[ScreameR]

100% upgrade scroll can only be used once like a normal upgrade scroll or BUS for example, instead it is a 100% success scroll up to +7 and also works on +2/3/4/5/6, which means it can't be used to +8 or higher. It would be a big waste to use it for example to +5, since it's really hard to get. If i'm right only Special monster staffs from PUS can drop them.

[BeastyBoy]

I really wish there weren't so many PUS items nowadays... I want to come back without spending money like on the old KO's but idk if its possible because of all the PUS items