There appears to be a bug with the way Hot Streak Pyroblasts (known as Pyroblast! with the exclamation point) functions in macros. You cannot do /cast Pyroblast! as a macro, the game doesn’t recognize it. You also cannot add Pyroblast without ! to a castsequence macro because if you do so, and the Pyroblast casts with a Hot Streak proc, then it breaks the macro.
History of Pyroblast! being used in macros from original Cata can be found in these spell articles on WoWhead.
Example of castsequence macro: if you attempt to use the macro below, if Hot Streak is active by the time you reach the Pyroblast part, it will cast the Pyro instantly, then stop working.
/castsequence reset=target Scorch, Living Bomb, Fireball, Fireball, Fireball, Fireball, Fireball, Pyroblast
If you read the above comments, it appears the additional Pyroblast! spell was created to avoid Pyroblast Hot Streaks proc’ing off itself. However, based on the above issues with Pyroblast! being used in a macro, and the way using Pyroblast in a castsquence breaks the macro, I’m wondering if Hot Streak not realizing there are supposed to be two different spells. In other words, could this also mean that Pyroblast is able to proc Hot Streak off itself, because there is no differentiating Pyroblast! spell being recognized? Or is this just exclusively an issue with macros in Classic Cata (ie - Pyroblast! in a macro worked in original but doesn’t work in 2024 Cata)?
Would be very interested if anyone has insight into this or if Blizzard is aware of this issue. Thanks so much!
EDIT: Did some more digging and it appears the “Pyroblast!” spell was removed in Original MoP for some reason. It should currently be in Cata Classic, though my guess is this will be a low priority bug since technically Hot Streak procs are working outside of macros and MoP Classic will release sometime next year. 