Bonds of the Elements. The four elemental guardians are linked together. When one of them dies, the others gained access to new abilities:
If Aqua dies, Ignis gains access to Fire Aura.
If Aura dies, Ignis gains access to Flame Whirlwind.
If Terra dies, Ignis gains access to Burst of Lava.
FIre Aura. At the start of each of Ignis's turns, each creature withing 5 feet of it takes 3 (1d6) fire damage, and flammable objects in the aura that aren't being worn or carried ignite. A creature that touches Ignis or hits him with a melee attack while within 5 feet of him takes 3 (1d6) fire damage.
Fiery Weapons. Ignis's weapon attakcs are magical. When Ignis hits with any weapon, the weapon deals an extra 1d8 fire damage (included in the attack).
Multiattack. Ignis makes two longsword attacks.
Longsword. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8+4) slashing damage plus 4 (1d8) fire damage.
Flame Whirlwind (Recharge 5-6). Ignis creates a 5 feet wide whirlwind of fire that move in a 60 foot straight line. Each creature in that line must make a DC 15 Dexterity saving throw. On a failure, a target takes 10 (3d6) fire damage and are ejected 10 feet in the air. On a successful save, a target only takes half as much damage and is not lift into the air.
Burst of Lava (Recharge 6). Ignis stomps the ground with his foot, causing crackling rocks filled with lava to erupt at four different points he can see within 30 feet of him. At the start of his next turn, the rocks explode. Each creature in a 20 foot radius sphere centered on each rock make a DC 15 Dexterity saving throw. The sphere spreads around corners. A creature takes 7 (2d6) fire damage and 7 (2d6) bludgeoning damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one fiery burst is affected only once.