Mind Blast: which rank to use

Priest · Shadow · 9 ranks, 4 learned by level 30.

At level 30 with 45 spell power, Mind Blast rank 1 gets the most damage per mana; rank 4 does the most damage per second.

Most mana-efficient rank by gear: rank 4 up to 32, rank 1 from 33 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 10)	61 (59–63)	50	1.5 s	1.23	40.9	4 min
Rank 2 (level 16)	92 (89–95)	80	1.5 s	1.15	61.2	2 min 30 s
Rank 3 (level 22)	126 (122–129)	110	1.5 s	1.14	83.9	1 min 49 s
Rank 4 (level 28)	173 (169–178)	150	1.5 s	1.15	115.4	1 min 20 s

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

Rank 1: 61 damage for 50 mana in Forever instead of 56 for 50 in Classic Era (spell power share 0.429 instead of 0.268).
Rank 2: 92 damage for 80 mana in Forever instead of 96 for 80 in Classic Era (spell power share 0.429 instead of 0.364).
Rank 3: 126 damage for 110 mana in Forever instead of 141 for 110 in Classic Era (spell power share 0.429 instead of 0.429).
Rank 4: 173 damage for 150 mana in Forever instead of 194 for 150 in Classic Era (spell power share 0.429 instead of 0.429).

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.