Sources
CR
Type
Size
Alignment
Movement

Cosmotronic Blastseeker

Medium Humanoid (any race), Chaotic Neutral

Armor Class 15 (chain shirt)
Hit Points 37 (5d8 + 15)
Speed 30 ft.
STR
14
+2
DEX
15
+2
CON
16
+3
INT
18
+4
WIS
9
-1
CHA
12
+1
Saving Throws DEX +4, CON +5
Skills Arcana +6, Intimidation +3, Perception +1
Senses passive Perception 11
Languages any one language (usually Common)
Challenge 4 (1,100 XP)

Traits

Empowered Spell (3/Day). When the blastseeker rolls damage for a spell, it can reroll up to four dice of damage. It must use the new dice.

Tides of Chaos (1/Day). The blastseeker makes one attack roll, ability check, or saving throw with advantage.

Spellcasting

Innate Spellcasting. The blastseeker's innate spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks). The blastseeker can innately cast the following spells, requiring no components other than its Izzet gear, which doesn't function for others:

2/day: fireball

3/day each: scorching ray, shield, thunderwave

Actions

Warhammer. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit:6 (1d8 + 2) bludgeoning damage, or 7 (1d10 + 2) bludgeoning damage if used with two hands.

Lore

While chemisters focus on inventing new tools, weapons, and other devices for the guild to use, the role of a blastseeker is to put those devices to work. Despite the name, not all such devices produce explosions, but all the most interesting ones (from the Izzet perspective) do.