When Morgan, Guin or Igraine Artifacts or "of Magic" items are used program multiplies by 1.5 then rounds down. When an Artifact and "of Magic" item are both used program multiplies by 1.5, rounds down, multiplies by 1.5 again and rounds
down again. Program doesn't multiply by 2.25 and round down. This can be seen by checking level 5 skill which delivers 10
rather then 11.

Based on above tested skill levels(double rounded multiplier) 28(63), 29(64), 57(127), 58(130) and 63(141). Testing was done using meteor shower (8+magic level damage) on Minotaurs.

MM6-v1.0 double rounded multiplier skill levels delivered following damage: 28(63)-71, 29(64)-8, 57(127)-71, 58(130)-10 and 63(141)-21.

MM6-v1.1, v1.2 and Mok's double rounded multiplier skill levels delivered following damage: 28(63)-71, 29(64)-72,
57(127)-135, 58(130)-138 and 63(141)-149.

Appears v1.0 has 8 bit limit on rounded multiplier which is why damage reset at levels 29 and 58. Interesting that levels 28 and 57 are exactly 8 and 9 bits, respectively.

Tested same skill levels around 8 & 9 bit levels using Dragon Breath.

MM6-v1.0 double rounded multiplier skill levels delivered following damage: 28(63)-948, 29(64)-0, 57(127)-864 and
58(130)-24. Yes, zero for 29(64). 64 and 128 both equal 0 skill level.

MM6-Mok's double rounded multiplier skill levels delivered following damage: 28(63)-901, 29(64)-900, 57(127)-1823 and
58(130)-1776. Had a level 57 shot that killed 2 Minotaur Kings and 3 Minotaurs, 2529 total HP.

Tested same skill levels around 8 & 9 bit levels using Day of Protection. MM6-v1.0 delivered same increases and durations as MM6-v1.1, v1.2 and Mok's.

Conclusions:
MM6-v1.0 can have magic skill levels built up to max of 28 w/ max double rounded multiplier skill level of 63. Constraint MAY only apply to offensive spells (not that that helps.)