Strong defence potion

The Strong defence potion is a one dose potion only available in the Dungeoneering skill. Using the potion boosts a player's Defence level by 6 + 20% of their Defence level.

It is made by adding Buckthorn and Void dust to a vial of water. This requires level 75 Herblore and grants 170.5 experience in Herblore. This potion can only be made in dungeons with complexity level 5+.

Reference

 * RuneScape Game Guide: Dungeoneering - Herblore Tables