Krotan

Krotan is a potent short term mutagen, which allows complete shape-shifting for the user. It was at one time quite popular amongst the upper classes of Thanagar – although it appears to have also worked for a variety of other alien races.

The primary Krotan dealer on Thanagar was Byth – who was also the head cop, so there was a slight conflict of interest. Eventually, Byth was overthrown and fled to Earth, now hopelessly addicted to Krotan – maddened both by the drug itself (seems his brain never uite made it back to its original shape) and by his subsequent withdrawal from it.