Updated.
I assume tendril => tentacle => slam. Or, in other words, all different ways of stating "bludgeoning attack".
Flame spirits speak their own language. When summoned to an area of the Prime Material Plane, they also speak languages common to that area. Their voices sound like hissing steam.
Like their cousins, fire elementals, flame spirits are native to the Elemental Plane of Fire. Flame spirits appear on the Prime Material Plane only if they have been summoned by magical means.
Flame spirits only can be conjured in areas of open flame. To provide a greater flame spirit with a suitable shell, a fire must be built that has a diameter of at least 5 feet. Once the flame spirit occupies this shell, it swells to its full size, 10 feet in diamter.
Flame spirits cannot pass over water or any other noncombustible liquids.
Vampires are also unable to cross running water, although they can be carried over it while resting in their coffins or aboard a ship.
A few misc. bits remain...
A least flame sprit is 1 foot in diameter and weighs x pounds. A lesser flame sprit is 6 feet in diameter and weighs x pounds. A greater flame sprit is 10 feet in diameter and weighs x pounds.
For comparison...
Fire Elemental Size/ Height / Weight
Small / 4 ft. / 1 lb.
Medium / 8 ft. / 2 lb.
Large / 16 ft. / 4 lb.
Flame spirits speak Ignan and (Common?). Their voices sound like hissing steam.
Can be summoned via summon spells for a fire elemental of the same size, but require an appropriately-sized fire as an additional material component?
Maybe give wu jen with fire mastery an additional flame spirit with each summoning, or some other benefit?
Cannot Cross Water (Ex): A flame spirit cannot pass over any body of liquid larger than itself, unless the liquid is combustible. Thus, a flame spirit could cross alcohol or oil, but not acid or milk.
Do we need to specify ice as well?