Blessed Light - Adding LEARN
Piston-Fist Cyclops - Adding LESSON
Springjaw Trap - Adding LESSON

Following update as well, but don't have the cards yet.

-3 of each color
-5 colorless
+2 of each guild (multicolor)

There is a lot of theme to build out into the multicolored slots, and a lot of redundancy in the monocolor slots. This should make for some interesting decisions in manabases and/or splashes.

Removing all regeneration, and updating some multicolored selections

540 cube had:
12 learn / 5 lesson per color
0 learn / 2 lesson per guild
3 learn / 10 lesson for colorless
63 learn / 55 lesson

Bumping to:
12 learn / 5 lesson per color
0 learn / 2 lesson per guild
3 learn / 13 lesson for colorless
63 learn / 58 lesson

Prefer to keep Deadeye Tormentor with a discard raid trigger, so adding Mardu Skullhunter with a learn raid trigger instead of ol' French vanilla Cursed Minotaur as the 12th black learn card. Cutting Aggressive Sabotage and putting back in Infernal Scarring as the 5th black lesson because I finally found one, and we don't need two Mind Rots at lesson.

Updating Aggressive Sabotage to Lesson as Infernal Scarring is not in this version.

Updating In Thrall to the Pit to Lesson as Messenger's Speed is not in this version.

Cutting Ondu Giant to get Prodigious Growth back in as the fifth green lesson.

This is my best guess as to the missing lesson for balance in the base cube.