it won't work in current core
Focus Spells are "implementation hell" in current core, The focus handling is very bad, properties that track who is casting and who is targetted are lost occasionally and suffer race-conditions, and these properties won't handle a "collection of target" so Focus can't be used to track spell targets on a AE-Effect
I had to put a lot of effort on Freyad to update Focus behavior to handle correctly actual focus spell (those known like focus shield, or focus shell, pretty common to use) and later Focus spells like Heretic or Bainshee
Get your hand on Branch/Freyad/Spellhandler.cs (it's not the complete path...) in DOL SVN, I had to implement totally new mechanisms to handle evolved focus spells, tracking each target on every focus pulse to correctly enable or disable game effect depending on range/distance from AE center/focus interrupt...
This is meant to go in DOL Core, I was still hoping to finish merging before end of the month but there is a lot to do
