The Ardougne teleport scroll is a scroll that you receive from the quest Plague City. You receive it as a reward at the end of the quest. When you read it, you learn the Ardougne Teleport (requires level 51 Magic), although reading the scroll itself does not have a magic level requirement.
If you get an extra Ardougne teleport scroll before using it and try to use both, the first will enable the spell, while any spare ones obtained will explode on use, leaving behind ashes. To retrieve another scroll if you lose yours, head back to Edmond; who has an infinite amount.
The scroll explodes.