After the first sing, the subcommander doesn't seem to listen to the song even though he's still awake. I don't think I've ever gotten that message about the guard already being knocked out on other mobs slept by cold be sleep. This is in Velkyn Oloth by the way.



A guard room
You stand in a rather large room with a table and chairs in the
middle. Some crude bunks are set by the walls and a few lanterns
dimly illuminate the surroundings, ideal for taking a break. A
few empty bowls and stained eating utensils lie strewn on the
table, only recently used. A doorway leads back to the corridor
to the west.


Groupmate is here.
Groupmate is here.
A guard sits here by the table, enjoying a meal.
A guard sits here by the table, enjoying a meal.
A guard sits here by the table, enjoying a meal.
A dark-elf waits by the table, her pitch-black armor glinting dully.

<100%hp 97%m 87%mv> sing cold
You sing 'Cold be hand and heart and bone,
And cold be sleep under stone:
Never more to wake on stony bed,
Never, till the Sun fails and the Moon is dead.'
The elite guard resists the power of your song.
The elite guard falls into a deep sleep.
The elite guard falls into a deep sleep.
The sub-commander of the guards resists the power of your song.

<100%hp 92%m 87%mv> sing cold
You sing 'Cold be hand and heart and bone,
And cold be sleep under stone:
Never more to wake on stony bed,
Never, till the Sun fails and the Moon is dead.'
The elite guard resists the power of your song.
The elite guard is already knocked out.

<100%hp 90%m 93%mv>