Pyroblast: which rank to use

Mage · Fire · 8 ranks, 3 learned by level 30.

At level 30 with 45 spell power, Pyroblast rank 1 gets the most damage per mana; rank 3 does the most damage per second.

Most mana-efficient rank by gear: rank 3 up to 14, rank 2 from 15 to 25, rank 1 from 26 spell power.

Every rank at level 30 with 45 spell power

Rank	Damage per cast	Mana	Cast	Damage per mana	DPS	Mana lasts
Rank 1 (level 20)	232 (216–248)	125	6 s	1.86	38.7	1 min 12 s
Rank 2 (level 24)	272 (253–292)	150	6 s	1.81	45.4	1 min
Rank 3 (level 30)	339 (315–363)	195	6 s	1.74	56.5	46 s

DPS counts the global cooldown. Mana lasts: casting only that rank from 1,500 mana.

Rank 1: 232 damage for 125 mana in Forever instead of 300 for 125 in Classic Era (spell power share 1.600 instead of 1.600).
Rank 2: 272 damage for 150 mana in Forever instead of 365 for 150 in Classic Era (spell power share 1.600 instead of 1.600).
Rank 3: 339 damage for 195 mana in Forever instead of 459 for 195 in Classic Era (spell power share 1.600 instead of 1.600).

From the client, for each rank: base damage or healing and its range (SpellEffect base points and variance), the extra per level up to the rank's max level, the spell power share (coefficient), mana cost, cast time, duration, global cooldown and cooldown.
No downrank penalty in the Forever client. Classic Era's client puts a penalty for spells learned before level 20 inside the coefficient (Shadow Bolt rank 1: 0.14); Forever's client gives the full share (0.486), for 80 low-level ranks across the classes. Anything else would be on Blizzard's servers, so the calculator shows Classic's rules only as Speculation.
Speculation: crits count only on direct hits, at 150%, as in Classic; the example gear (1.5 spell power per level) is not client data.