Shade
Monster Junkie
Some comparable creatures for CR estimation:
Ancient Red or Silver Dragon (34 HD) - CR 23
Wyrm Red or Silver Dragon (37 HD) - CR 24
Mountain Landwyrm (40 HD) - CR 22
Swamp Landwyrm (36 HD) - CR 20
She seems less deadly than a wyrm red or silver dragon (20d10 breath weapon damage seems more powerful to me than choking, and her other abilities, while powerful, don't match the abilities of a 17th-level spellcaster). However, she could beat the stuffing out a mountain landwyrm, so I'd place her at CR 23.
I say double the weight of the tarrasque. She has a body shape more similar to it than to the titans.
Suggested languages: Common, Draconic, Auran, Terran.
Ancient Red or Silver Dragon (34 HD) - CR 23
Wyrm Red or Silver Dragon (37 HD) - CR 24
Mountain Landwyrm (40 HD) - CR 22
Swamp Landwyrm (36 HD) - CR 20
She seems less deadly than a wyrm red or silver dragon (20d10 breath weapon damage seems more powerful to me than choking, and her other abilities, while powerful, don't match the abilities of a 17th-level spellcaster). However, she could beat the stuffing out a mountain landwyrm, so I'd place her at CR 23.
I say double the weight of the tarrasque. She has a body shape more similar to it than to the titans.
Suggested languages: Common, Draconic, Auran, Terran.