Dream Vestige Question

[D&DPrinceTandem]

So this has been bothering me for a while now; the Dream vestige from Libris Mortis has a kinda useless ability unless there is fine print to which I am blind to
This is my issue

When a dream vestige gains a number of temporary hit points equal to its full normal hit point total, it self spawns, splitting into two identical dream vestiges

it’s only ability to gain temporary hit points give 5 Temporary hit points. I am pretty sure Temporary hit points Are notorious for not stacking. This would mean that some outside source would have to, in one go, grant it 110 Temporary hit points to proc this ability (a Manifester level 22 sangehir, manifest a fully Augmented Vigor on it) Now I know how to do this, but it kinda feels strange that it needs outside influence..

[Bohandas]

Does it say it needs all of them at once?

[daremetoidareyo]

Damage it down to 5hp.

[Thurbane]

As per Rules Compendium:

Temporary hit points gained from multiple applications of the same effect don’t stack. Instead, the highest number of temporary hit points gained from that effect apply.

Having said that, this is an excellent point:

Does it say it needs all of them at once?

IMHO, the ability could have been worded a lot more clearly, but for it to work at all, you either need to let temp HP stack, in spite of the general rule; or track temp HP over time, and it spawns once it hits this total.

Damage it down to 5hp.

...would not work due to the ability wording:

When a dream vestige gains a number of temporary hit points equal to its full normal hit point total, it self spawns, splitting into two identical dream vestiges, each with a number of hit points equal to the original dream vestige’s full normal total.

[Particle_Man]

Would dropping a dream vestige into the positive energy plane make a dead dream vestige or would it create an ever-growing group of them?

[Kelb_Panthera]

Would dropping a dream vestige into the positive energy plane make a dead dream vestige or would it create an ever-growing group of them?

Strictest RAW interpreted like code; the latter.

That said, I have a hard time imagining any GM would have the positive energy of the plane not destroy undead post-haste.

[Particle_Man]

Thus the plane of positive energy changed to the plane of fearful dreams, just as the plane of fire changed to the plane of brown mold.