Yeah Geo is a really good skill to invest, because of Heart of Steel (even tho it is a poly skill).
This being a regen skill that still gives you a massive boost to your pool unlike the magic armour skills.
Still if you properly min max you have no room for more than 2 Geo, because of Scoundrel. (I only started going it after I maxed Warfare, because my Int is now getting close to the cap and I can start going Wits).
Also the full combo with bonecage isn't always worth it, because often you can start an encounter with Heart of Steel, Fortify + Reactive Armor, the damage on this is high enough to oneshot an enemy group standing close to each other, now you have corpses and can cast Bonecage for much more armor, use Blood rain and Grasp (Executioner will provide 4 AP back), use Adrenaline and if you have to either Skin Grasp or depending on the number of enemies kill some single targets first with your single necro skills (2 ap each from executioner again) and then Skin Grasp for reset of all cds.
Shackles looks good on paper but afaik you need to remove phys armour first for it to apply (I might be wrong never tested it) but most times you will just kill people including their phys armour...
