[Squirrelloid]

The following assumes vanilla for all pretenders:
An imprisoned dom 5 3x9 Frost Father requires -12 net scales in vanilla... Hardly an optimal bless chassis, and I wouldn't say there's much left over there. Even assuming a rainbow, you can do the same with a Great Enchantress, except you get a better bless and a pearl every turn. (E9S9X9 >> W9A9X9)

For one extra negative scale, we can have a great mother with E9N9X9 (great bless!). Of course, E9X9N8 is probably better for a lot of nations, so we squeeze out some extra dominion or only -11 scales instead.

You could take a Phoenix with identical build style (dom5, 3x9, imprisoned, -12 scales), have at least an equivalent bless (F9A9X9), and a better pretender chassis (flying, immortal). Also in this category: Titan (A9E9X9, and its a titan chassis so it can be an SC when it wakes up), Keeper of the Bridge (A9E9X9, Titan Chassis), Moloch (F9B9X9, Dom 6!, great chassis), Mother of Tuathas (A9N9X9, titan), Destroyer of Worlds (A9D9X9, titan, 4 arms!), and so on...

With similar build but better blesses (and chasses), there's the Lady of Love (W9N9X9, titan chassis, Awe+4), Mother of Serpents (D9N9X9, titan chassis), PoD (D9X9Y9 - more versatile, excellent chassis), Mother of Spring (W9N9X9, titan chassis, produces water gems), Lord of the Forest (E9N9X9, titan chassis, dom summons animals), Father of Serpents (D9N9X9, Titan, good stats), Lord of Plenty (E9S9X9! titan), Scorpion King (F9E9X9!, great chassis), and so on...

Getting more efficient at 3x9 blesses, we have the master lich (Dom5, only -11 scales), and its also immortal. There's also the Lord of Rebirth (E9N9D9, titan chassis, -11 scales, Dom 6!), Colossal Head (N9B9X9, -11 scales, Dom 6), Smoking Mirror (F9D9B9, -10 scales, Dom 6!! Of course, you probably take B8 instead of B9 and grab more dominion), Jade Emperor (W9A9S9, Titan, -10 scales), Lady of Fortune (W9S9X9, -11 scales, titan), and so on.

Of course, you could just take a monolith, get Dom 6, and only need to take -11 net scales. Oh yeah, and still have a better bless. (S9N9X9 >> W9A9X9).

Or there's the perennial favorite, Oracle, which with -12 scales and a very versatile triple bless (S9X9Y9) can also swing Dom 9. Not only is it one of the best triple bless chasses in the game, its also available to most nations. Its best competition is Divine Glyph, which is slightly cheaper (Dom 10 with -12 scales), but its bless is more constrained (F9S9X9). Fountain of Blood is just as efficient as the Oracle, but you get B9 instead of S9 (worse bless). Sacred Statue is also S9X9Y9, but slightly more expensive because of chassis cost.

Getting a 3x9 bless is easy, and frost father is one of the *worst* chasses for it.