survival instincts:

The chimera being young is far too cautious, and will run away from groups of adventurers. It will often run away, use its fireball, and claw towards single opponents. Having three heads has it’s benefits, being too cautious for a player to stealth their way towards it in combat with its 360 degree view.

Multiattack. The chimera makes three attacks: one with its bite, one with its horns, and one with its claws. When its fire breath is available, it can use the breath in place of its bite or horns.

Bite. Melee weapons: The young chimera’s snake head attempts to bite in a range of 5ft, +1 to hit (1d8+2) piercing damage. Single target 

Horns. Melee Weapon Attack: a feeble attempt headbutt with its dull goat horns in a 5ft, 180 degree radius (1d4+2) bludgeoning damage

Claws. Melee Weapon Attack: A silly pounce that allows the chimera to jump 15 ft and claw. +3 to hit (1d8) piercing damage.

Fire Breath???  The chimera charges up a firey blast and… a blob of acid flies out in a 30 ft radius and sets up a 4x4 (20 ft x 20ft) of acidic floor that does 1d4 every attempt to stand/walk through it. The blob flies way too high up to collide in the air, with the chimera choosing its AoE location. The floor lasts for two rounds, and the “attack” has a three round recharge

No bonus actions

.