In current stage of the game this gem sticks out as of very little use for any class and kind of build.
15% chance on hit to gain a Wreath of Lightning, dealing 1250.0% weapon damage as Lightning every second to nearby enemies for 3 seconds.
• While under the effect of the Wreath of Lightning, gain 25% increased movement speed. (Requires Rank 25)
Description kinda speaks for itself. 15% chance is very low, damage output is not relative to anything. Wizard and monk still have better picks.
Movement speed locked at 25% is also not a big deal especially if it depends on 15% proc chance.
Editing movement speed buff to stable 50%-100% active at all times with 0,5% or 1% progress per level accordingly would create some nice movement speed gem which is lacking in the game. In many builds it is necessary to sacrifice damage or survivability for speed.
It could be fixed with redesigning gem which basically nobody uses anymore.