Kaos can breathe in round 509. If, by blindsense, you are referring to the debris thrown up by hovering, Kaos is not big enough to do that.
Round 508: RB steps up next to Kaos, stomping (rolled 22) for 7. Kaos has 100 HP. As she steps back down, Kaos bites her for 6. RB has 30 HP.
Kaos bites for another 9. RB at 21 HP.
Round 509: RB misses all three attacks. Kaos breathes acid for 18. RB at 3. Kaos can breathe in round 511.
Round 510: RB misses with hoof. Kaos hits with AoO for 4. RB is dying. (Yay!) (CR 7?)
Kaos has 100 HP and is at 30N60E10Z.
A huge lizard with eight heads runs to 30N65E. Kaos recognizes it as a hydra, and knows that it has the scent ability, that it heals really fast, its magical beast traits, that it can make a full attack even when charging or moving, and that you can kill it by cutting off its heads one at a time (by sundering with a slashing weapon) and applying fire or acid to the stumps.
Round 508: RB steps up next to Kaos, stomping (rolled 22) for 7. Kaos has 100 HP. As she steps back down, Kaos bites her for 6. RB has 30 HP.
Kaos bites for another 9. RB at 21 HP.
Round 509: RB misses all three attacks. Kaos breathes acid for 18. RB at 3. Kaos can breathe in round 511.
Round 510: RB misses with hoof. Kaos hits with AoO for 4. RB is dying. (Yay!) (CR 7?)
Kaos has 100 HP and is at 30N60E10Z.
A huge lizard with eight heads runs to 30N65E. Kaos recognizes it as a hydra, and knows that it has the scent ability, that it heals really fast, its magical beast traits, that it can make a full attack even when charging or moving, and that you can kill it by cutting off its heads one at a time (by sundering with a slashing weapon) and applying fire or acid to the stumps.