[MTG] Enemy-Color Tribal-Class Set [280 Cards]

[Knitifine]

Vigilance is allowed in green on big creatures. 2/2 is not big.

Tends to, is not the same thing as 'forbidden'. Green can have smaller vigilance creatures if that's what helps the set. Much like how green can have really good haste creatures despite it being tertiary.
EDIT: Also worth noting, anything that takes away from white's slice of the color pie is fine with me as I believe white has been over-inflated by the designers since the creation of modern.

Arm the Forces technically does literally nothing.

This needs elaboration in order for me to understand the mistake.

Midnight Sermon's second mode could just be "Mourn", since Mourning a creature isn't established/used anywhere else and the distinction is a corner case that will almost never matter.

It's TBD for the definition, but it definately should be Mourn that creature since the intention is not to allow mourning of other creature cards that have been placed in the deck (if it didn't specific you would be allowed to choose. Wording incoming.)

Goblin Wizard looks overcosted by 1. I'm not entirely sure, but it feels off.

That'll be a development concern. It's possible, several of the most recent cards I added are deliberately overcosted for drafting purposes.

The Cleaner should (I think) be:
(T): Add 1 to your mana pool. Spend this mana only to pay the cost of Burial.
or
(T): Until end of turn, the cost of Burial is reduced by 1.

Yeah, it's the latter. Though I'll have to check the formatting development uses, I don't remember them using (T).