Source: Borne by the Sun's Grace, pg(s). 84
A tletli couatl is a massive serpent whose iridescent scales seem to reflect light like an opal. Its feathered wings are shrouded in flames, ranging from orange at the base to blue at the tips. The flames can even burn creatures made of flame and are especially effective against undead, evil outsiders, and dragons. A typical tletli couatl is 35 feet long with a wingspan of 25 feet, and weighs almost 6,000 pounds.
Tletli couatls do not hunt down individuals but target whole groups that they consider to be beyond redemption, and channel their righteous fury to destroy them, offering no salvation.
Tletli couatls occasionally offer their feathers to mortals, who can use a tletli couatl's feather to summon the specific tletli couatl without the need for payment, if the tletli couatl approves of the service that the mortal asks it to do.
Tletli couatls serve as executioners, exacting punishment on irredeemable regions. Before doing so, they typically enlist mortals to extend a final chance for redemption for their quarries. If there are innocents in the company of the tletli couatl's targets, it might forewarn them by sending a charmed emissary, but does not hesitate to burn the entire group to ashes, as its prerogative is punishment, not mercy. Because of this, their masters usually send other celestials to accompany tletli couatls to evacuate or protect innocents during the tletli couatl's razing.