All BLM needs is speed, raw power never scales well vs %s unless speed is included.
Yoshi could even include it as ab extension of the Enochian language to spell the word for "fast" using Umbral hearts/Foul.

Foul would hold the first 2 phonetics for Fast
Blizzard 4 would hold the last 2
By the time 2 fouls occur it will spell fast in enochian resulting in instant casts X number of umbral hearts or just 3 solid insta casts per 2 fouls and 2 b4s.
Tie the activation to hitting the Enochian button while its already active to activate OrUnFamGisg.

Or IPZI.