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Jekyll and Hyde was a random event before the 25 February update. Occasionally, the player would be approached by a man named Dr. Jekyll who desperately begged for help. Dr Jekyll approached the player and asked for the highest level clean herb that the player had; he asked for Guam Leaf if player had no herbs. In return, Dr Jekyll would give the player a potion (see list). A player could choose not to help, then Dr Jekyll would go find someone else to help him and the player received a strength potion(2).

If the player ignored him, he would transform into Mr Hyde (level 14-159, depending on the player's combat level), who fought with melee. When killed, he would drop a potion, similar to if he was given a herb. However, sometimes he dropped an empty vial. Killing him could sometimes be more profitable than giving him a herb, as he could possibly drop a Super restore potion (4), although this is no longer possible.

Since the release of HD, Hyde had this "tentacle effect" graphic glitch, which was fixed on 29th July 2008.

The list, which potion Dr. Jekyll gave for the herb:

*For Ranarr and above, the potion given is 1 level below the herb

Trivia

• The event is a direct reference to the mystery novel Strange Case of Dr Jekyll and Mr Hyde by Robert Louis Stevenson. It is about a doctor who created a potion, splitting himself into two distinct personalities. He existed as the kind, gentle Dr. Jekyll, and the fearsome, malevolent Mr. Hyde.

• If a player were to receive this random event underwater, Jekyll would be wearing diving gear.
  

  Jekyll underwater!

• If a player used a fairy ring during this event, Jekyll would follow the player through the ring! This is despite his seeming human appearance and thus the need to wield a Dramen staff or Lunar staff to use fairy magic. Jekyll wields neither item.

• Occasionally player will see Dr. Jekyll visit the Apothecary in Varrock.