This had happened once before, only that time he managed to hit the opening cranial on a sleeping person who had been knocked out by cranial. Unless there has been a change, I seem to remember that if you get knocked out by cranial you get protection from the skill for a certain amount of time.

From Code-Changes board:

- Cranial as an opening move is like blackjack. You cannot do it repeatedly, and it offers the victim protection against future cranials for a while.


<368/689hp 467m 794mv 13780tnl (2.13%)| 6 PM |civilized> e
Alas, you cannot go that way.

<368/689hp 467m 794mv 13780tnl (2.13%)| 6 PM |civilized>
Along the Eastern Road


A sign points south towards the Drogran Hills.
(Black Aura) Ecekai is here.
Ecekai strikes you over the head with a long elvish mace.

<368/689hp 467m 793mv 13780tnl (2.13%)| 6 PM |civilized> s
In your dreams, or what?

<368/689hp 467m 793mv 13780tnl (2.13%)| 6 PM |civilized> aff
You are affected by:
Timer: 'physical sleep protection' for 6 hours.
Skill: 'cranial' for 2 hours.
Spell: 'detect invis' for 0 hours.

<368/689hp 467m 793mv 13780tnl (2.13%)| 6 PM |civilized>
Your eyes no longer pierce the shroud of invisibility.

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized> flee
flee
q 'green potion'
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized>
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized> flee
flee
q 'green potion'
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized>
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized>
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized>
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized> flee
In your dreams, or what?

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized> flee

Ecekai's cranial hit misses you. <--- This is wierd
Ecekai is in perfect health. (100%)

<463/689hp 473m 839mv 13780tnl (2.13%)| 7 PM |civilized>
Along the Eastern Road


A bloody skin made from a corpse lies here.
You flee from combat!

<463/689hp 473m 838mv 13780tnl (2.13%)| 7 PM |civilized> w
s
Along the Eastern Road


A sign points south towards the Drogran Hills.
(Black Aura) Ecekai is here.

You get protection from actually being knocked out again, not from every potential cranial.