These should be fairly easy. We can probably modify the blink dog's stats (Str 10, Dex 17, Con 10, Int 10, Wis 13, Cha 11) slightly. Compared to a 2e blink dog, the damage is doubled, Int skews 2 points higher, bonus hp are 8 better, and AC is 1 better.
So maybe Str 18, Dex 19, Con 18, Int 12, Wis 13, Cha 13?
It may also activate the following spell-like powers at will, one per round, at the 6th level of ability: detect evil/good, diminution (as per the potion), enemy detection (as the wand), find the path (or its reverse), haste (once per day), invisibility, polymorph other (once per day), and polymorph self (to humanlike form only).
That polymorph self should become change shape, like a genie. Diminution could work like reduce self, but apply to the rummele.
I'm not sure what to do with enemy detection.
A rummele may also create food and drink and other non-metallic items as a djinni does.
That would be...
1/day—create food and water, create wine (as create water, but wine instead), major creation (created vegetable matter is permanent).
A rummele has infravision and ultravision out to 90’, and can regenerate 1 hp per turn. This regenerative power can be transferred to one other being, by touch, for as long as physical contact is maintained.
Darkvision 90 ft. and low-light vision?
I think fast healing makes more sense here than regeneration.
The rummele is immune to diseases, poisons, effects of the Positive and Negative Material Planes (including life-level draining), and to petrification and polymorph effects.
Immunity to death effects, disease, poison, petrification, and polymorph?
Borrow this?
Divine Equilibrium (Ex): Movanic devas are immune to the effects of negative-dominant or positive-dominant planar energy traits (see Chapter 1 in Manual of the Planes).
It is immune to certain will-force spells as if it had a 20 wisdom (see the DEITIES & DEMIGODS. Cyclopedia).
I'll have to look this up.
These agile creatures can dodge ordinary missiles or knock them out of the air on a roll of 8 or better on 1d20.
Deflect Arrows as a bonus feat? Maybe evasion or improved evasion?
They have prehensile paws and flexible joints, and may climb walls as 10th-level thieves. If they fall, they take no damage for the first 30’ of the descent, taking normal damage afterwards (4d6 for 40’) etc.).
We can just give 'em a climb speed for the former, and slow fall like a monk for the latter.
Rummeles cannot be surprised because of their keen senses and high dexterity.
Racial bonus on Listen and Spot checks?