Keen Sight. The cat-dragon has advantage on Wisdom (Perception) checks that rely on Sight.

Scamper by. the cat-dragon does not evoke attacks of opportunity

Catfall. the cat-dragon is immune to falling damage

Catty Stealth. the cat dragon has advantage in stealth checks while moving at half speed or less. any attempts to detect the cat dragon by sound is done at a disadvantage.

Evasion. The cat-dragon can nimbly dodge out of the way of certain area effects, such as a red dragon's fiery breath or an Ice Storm spell. When it is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, it instead take no damage if it succeed on the saving throw, and only half damage if it fails.

Cating action. The cat-dragon can take a Bonus Action on each of it's turns in Combat. This action can be used only to take the Dash, Disengage, or Hide action.

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Innate SpellCating. The cat-dragon's spellcasting ability is wisdom (spell save DC 18). The cat-dragon can innately cast the following spells, requiring no material components:

At will: Silent Image, Catnap, Charm person

3/Short Rest each: Invisibility, Nondetection, Major Image.

1/Short Rest each: Greater Invisibility, Hallucinatory Terrain, Mislead, Seeming

the cat-dragon regains use of all its spells after every short or long rest.

Multiattack. The cat-dragon can use its Frightful Presence. It then makes four attacks: one with its bite, one with it's tail and two with its claws.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 28 (3d10 + 12) piercing damage.

Claw. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 22 (3d6 + 12) slashing damage.

Tail. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 25 (3d8 + 12) bludgeoning damage and the target must make a strength saving throw (DC 18) or fall prone.

Frightful Presence. Each creature of the cat-dragon's choice that is within 120 feet of the cat-dragon and aware of it must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the cat-dragon's Frightful Presence for the next 24 hours.

Uncatty dodge. When an attacker that the cat-dragon can see hits it with an attack, it can use it's reaction to halve the attack’s damage against it.

Catposition (Recharge 5-6). when the cat-dragon is hit by an attack and the attacker can not see the cat-dragon, the cat-dragon may teleport to switch places with another creature within 30 ft of it which is not the attacker, that creature is hit by the attack instead. 

The cat-dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The cat-dragon regains spent legendary actions at the start of its turn.

Detect. The cat-dragon makes a Wisdom (Perception) check.

Charging Claw Strike. The cat-dragon can move up to 30 ft, makes a two claw attacks, then moves up to 30 ft more.

Tail. the cat dragon makes one tail attack 

Wing Attack (Costs 2 Actions). The cat-dragon beats its wings. Each creature within 10 feet of the cat-dragon must succeed on a DC 18 Dexterity saving throw or take 22 (3d6 + 12) bludgeoning damage and be knocked prone. The cat-dragon can then fly up to half its flying speed.