Crazy me with a crazy question …

There's no information at the DDO Wiki for this SLA, and I've become curious.

I'm levelling a Ftr6/Rog13/1Wiz TWF Assassin/Kensei: Weapon Finesse & Assassin3 Core for Dex to Attack & Damage with Rapiers; Greater DM for Displacement SLA with Extend MM …

The character build will include Measure the Foe III and Assassinate, plus other strikes that procc either Sneak Attack Dice, or hit with both weapons.

I've stripped all of the PrE trees bare of all items for which I might have use (I don't have access to any of the Universal PrE trees): at Lvl20 I'll have 2 APs left-over, unassigned and dangling.

DM Focus III and Binding Shadows seem to be the only selections that might be worth taking: DC should be based on character-level, and the style of debuff might come in handy, but I've got no information.

Is the DC borked/broken; is it only a Will Save, or a dual-Save like Phantasmal Killer; are there mobs that are immune; what's the duration?

Does anyone have any good information?

GG