Keen Hearing and Smell. This Puppy has advantage on Wisdom throws that rely on hearing or smell.
Peak Tactics. The Puppy has advantage on an attack roll against a creature if at least one of the puppy's allies is within 5 feet of the creature.
Untamed Learning. Cassius can learn any fire-based spell once he has observed it being cast. (Limited to 1 spell per long rest).
Spellcasting. Cassius is a 4-level spellcaster. Its spellcasting ability is Dexterity (spell save DC 11, +4 to hit with spell attacks). Cassius has the following Evocation spells prepared:
Cantrips (at will): Create Bonfire
1st level (2 slots): Burning Paws
2nd level (2 slots): Continual Flame
3rd level (1 slot): Fireball
Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: (1d8 + 2) [piercing] damage plus 1d8 fire damage.
Fire Breath (Recharge 2). The Puppy exhales a 15-foot cone of flames. Each creature within that area must make a DC 17 Dexterity saving throw, taking 14 (3d8) fire damage on a failed save or half as much on a successful one.
Flaming Shield. This puppy can jump in front of any fire-based attack and absorb the flames while protecting any allies within a 20-foot sphere centered on itself.