What's the difference between Invulnerability and armor?

[Bone Tomahawk]

The Invulnerability spell and say the Ironskin spell, what is the actual difference? They all add a certain amount of protection if I am not mistaken?

[Eldritch Gentleman]

Invulnerability is negated by magic weapons, and interacts differently with armour. Ironskin adds to natural protection, which means that a unit with invulnerability 25 and heavy armour is nigh-unkillable without magic, whereas heavy infantry under ironskin will just be difficult to damage.

[Gregstrom]

I'm pretty sure Invulnerability just adds to natural protection in the same way as Ironskin (except of course that it's negated by magical weapons). It's mostly inferior to the other buffs to natural protection, barring some niche cases (mostly involving not having E or N casters, being one of a couple of nations or fighting a specific nation/army).

[Eldritch Gentleman]

Originally posted by Gregstrom:

I'm pretty sure Invulnerability just adds to natural protection in the same way as Ironskin (except of course that it's negated by magical weapons). It's mostly inferior to the other buffs to natural protection, barring some niche cases (mostly involving not having E or N casters, being one of a couple of nations or fighting a specific nation/army).

According to the manual, invulnerability grants protection 15 or 25 (Depending on the source) against mundane weapons. I believe that means there's an additional damage v protection check before armour is accounted for.

[Manadh]

Invulnerability is applied to mundane damage (physical damage without magic weapons etc) if higher than armour; So invun 15 reduces all of said damage by 15 rather than using armour. Armour reduces mundane damage by it's own value, while pierce damage is only reduced by half of armour, and most magic is either armour negating (AN) which means it isn't affected by armour or armour piercing (AP) which halves the effectiveness of armour.

Ironskin raises the target's armour to 20, or if already 20 or greater increases it by 3 (from memory). Most invulnerability is invun 15 or 25.

Hope that helps :)

(Edit: corrections thanks to bad memory - thanks Zonk)

[Zonk]

Invulnerability *replaces* natural protection if higher than it (one assumes/hopes this, at least) and the attack is nonmagical.

Stygian Skin (and rains) give invuln 15, the Invulnerability spell gives 25 which is also what (correction: some) pretenders and vampires have.

Bark/stone/ironskin set protection to 10, 15 or 20 if lower than that, otherwise they give +1 / + 2 / +3 protection.
They also give -5 resistance to fire, cold and lightning respectively.

[Gregstrom]

Some Pretenders have Invul 15, IIRC.

[Zonk]

Originally posted by Gregstrom:

Some Pretenders have Invul 15, IIRC.

Right, there are more pretenders with Invulnerabile 15 than 25 actually (only the Virtue & Vampire Queen) have the latter.

Pretty big difference, 15 is nice if you have some real armor on, but by itself it won't make a pretender safe from even regular indies...