AS (in General)

i have Ablative Shield: 2,125,378/1,832,223 (1,062,699) but in battle against the char Critters who cast no enchantments and my as on gives me 700k worth of hp?

Play-by-play
Lorenzo vs. Critters
Robert The Bruce cast Dispel Magic on all enemy Minions (1,782,057)
William Wallace cast Ablative Shield on all friendly Minions (717753)
Hamish cast Guardian Angel on all friendly Minions (?)

enchantment effects that cannot be determined before combat are displayed as '?'
Ranged Combat
Princess Isabella's Magic missile hit Lee [433511]
Robert The Bruce missed Lee

Lee regenerated 41,100 HP

Princess Isabella's Magic missile hit Lee [583468]
Princess Isabella cries "Love? I wouldn't know!"

Lee regenerated 41,100 HP
R.I.P. Lee

casts at 68% of its level

to be exact, from wiki:

Ablative Shield casts for 50% of its Spell Level, though at lower levels this could be up to 68% (34 HP gain with level 50 Ablative Shield = 68%)

* With 1 minion you get 1 * 50% Ablative Shield efficiency. Total is 50% effectiveness.
* With 2 minions you get 2 * 50% Ablative Shield efficiency. Total is 100% effectiveness.
* With 3 minions you get 3 * 40% Ablative Shield efficiency. Total is 120% effectiveness.
* With 4 minions you get 4 * 36.25% Ablative Shield efficiency. Total is 145% effectiveness.
* With 5 minions you get 5 * 33.75% Ablative Shield efficiency. Total is 168.75% effectiveness.

You have four minions so the effect is 75% I think

5 minions*

multiplying the spell level (2mil) by the 5 minion rate of 33.75% puts your AS as being correct at 717k

AS gets weaker in effect as you have more minions, but the total amount of HP gained goes up. The stat would probably display the correct amount, but Familiars through the prediction off. So instead the it defaults to displaying the 1 and 2 minion amount.

It use to display a question mark for a brief period of time. If I remember correctly, it was right after AS accounted for Familiars when determining the HP gained. People complained and so Jon put a number to make some of them happy.