Archdemon

Special Trait Name. resistace to blugeoning piercing invulnerability unless hit by dragonbone or silverite

Spellcasting. The [monster name] is a #-level spellcaster. Its spellcasting ability is [ability score] (spell save DC #, +# to hit with spell attacks). The [monster name] has following [class name] spells prepared:
Cantrips (at will): [spell name], [spell name] 
1st level (# slots): [spell name], [spell name] 

Action Name. multi attack can attack 3 times per turn plus voice

Action Melee Attack. claw 2d10+7 claw 2D10+7 bite 1D10+7 strength saving throw of 18 to not get grappled

Action Ranged Attack. ethereal voice 3d10+12 damage target becomes ethereal for one round. can use twice per round voice of death Auto Kill unless DC 18 save con than dropped to one

roll between 1-50 see if he gets breath back

counter strike 12d6+12 twice per round roll to get back

Reaction Name. tail attack 1D10+12

Gust 2D12+12

Fly 150 ft

counter attack 4 uses per round

can be used on reactions and bonus actions fine between anyone turns

Legendary Action Name (Costs # Actions). can succeed on any saving throw 2 uses per round.can take half damage on any type of damage. 2 uses pr round 

have to roll between 1-50 to get them back

Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). regenerate max health 1 time per day