Base Class: Wizard
"AAAGH! AAAAAAH, OH, GOD, IT BURNS! IT BURNS!"
'Yes, that's rather the point.' - An exchange caught between a Sin'Dorei pyromancer and her victim.
While any worthy mage is an unparalleled expert in the use of magic and heavily dedicated to their craft, those who master the forces of fire tend to be a little more audacious than their peers. If a threat stands before them, the answer is always to neutralize it in a glorious blaze. A lifetime dedicated to the study of fiery forces only fuels their pyromania, and these mages take pride—even pleasure—in igniting their enemies in wild bursts of flame. Mistake their affinity for watching things burn as a lack of self-control at your own peril.
Blazing Barrier
Beginning when you select this school at 2nd level, you learn to shroud yourself in flame to protect yourself from attackers. When an enemy ends their turn within five feet of you, they must succeed a CON save = to 8 + 1/2 your Wizard level. If they fail, they take 1d6 fire damage. If they save, they are immune to this effect for 24 hours.
This damage increases to 1d8 at level 6, 2d6 at level 10, and 2d8 at level 14.
Hot Streak
Beginning at 2nd level, you learn to chain your spells together and (literally) fuel your own fire. After you deal at least 1 point of Fire damage to an enemy three times (any number of enemies, not necessarily the same one), you begin a Hot Streak. On the fourth spell, roll a d100: On a seventy-five or higher, you deal critical damage, dealing double the damage die and setting the enemy ablaze. On a twenty-five or lower, you lose control of the spell, and take the damage yourself- As well as catch yourself on fire.
Cashing in a hot streak is optional: However, it does not accrue. If you do not use it on the fourth consecutive spell, the counter resets.
Fireblast
Starting at 6th level, you learn to cast a quick, savage blast of flame. Twice per short rest, you can take a reaction to make a Spell Attack on a creature within 15 feet. If it hits, they take 3d6 fire damage and must roll a CON save = to 8 + your Wizard Level to avoid being blinded by incredible heat, and deafened by roaring flame.
Cauterize
Beginning at 10th level, you have learned the basic first aid applications of fire. When you would normally take a fatal blow, you siphon heat from the world around you inwards and use it to briefly cauterize your wounds. You recover 2d6 HP as temporary HP and remain standing. After a number of rounds equal to your INT modifier, you lose this temporary HP. If this reduces you back to 0 HP, you are incapacitated.
Living Bomb
Starting at 14th level, you learn to plant a seed of ever-growing fire magic inside a living target. Choose a target within 60 feet that you can see. This target must succeed a WIS save equal to your Spellcast save DC. If they fail, the target will explode after 1d4 rounds, dealing 5d8+10 Fire damage and 5d8+10 Force damage to the target, and stunning them. If they die from this effect, the explosion rips outwards in a fifteen-foot radius, forcing all targets within to make a DEX save equal to your Spell save DC, and dealing 10d8 Force damage to all targets in that radius that fail. If the target was wearing plate or chain armor, add an additional 2d6 Piercing damage to those within 5 feet of the center of the blast, 1d6 for those at 10 feet, or 1d4 for those at 15 feet. Targets that save take half the damage, and no shrapnel damage.