Azuth's Spell Shield

[Ewe]

Can someone explain this to me? It's not clear based on the description. It begins at 50 spell resistance and you get an additional one sr per caster level? I'm not sure how they get to 70 - 9 in the example otherwise. The wiki seems to not match this at all either, it seems to suggest the max would be 47 sr when cast on one person.

https://wiki.bgtscc.net/index.php?title ... ell_Shield

Caster Level(s): Clr 7
Innate Level: 7
School: Abjuration [Azuth]
Component(s): Verbal, Somatic
Range: Self
Area of Effect / Target: 8 feet radius
Duration: 1 round/level (see text)
Save: n/a
Spell Resistance: n/a

Faithful of Azuth and Mystra only.

Each friendly creature together with the caster in an 8 feet radius gains spell resistance for the duration of the spell. The duration and spell resistance amounts are decreased by three for every creature affected, beginning at 50 spell resistance and one round / casterlevel. When cast by a level 20 priest for a total party of three the three recipients would all gain Azuth's spell shield for eleven rounds (20 - 9 rounds), with 61 spell resistance each (70 - 9). In order to affect a creature who has spell resistance with a spell, a spellcaster must roll the creature's spell resistance or higher on 1d20 + caster level.

[Tsidkenu]

The original spell was 70 SR which was deservedly reduced to 50 (and you then remove 3 for each target affected, including the caster, meaning the maximum SR is 47). The spell description was never altered since its introduction.

[Valefort]

Changed.