MArcomage

Doesn't seem that much greater than its Uncommon variant. In fact, I think I'd rather draw Architect, which shouldn't happen. Maybe make it free, or 1 brick?

I would make it enduring. So it's harder to dispel than durable.

Enduring does not make the card stay on hand.
You could have "Summons Grandmaster bricklayer" instead?

Then we would have a architect academy which is not banishable and grants unlimited Quarry... I would not like the idea of having free durable facility gainer, it would turn facility or stock reducer useless and would feed the cost of any card. A spam of Siege golem would be no problem with this.

Oh geez, you're right about enduring. I need to remake one of my concepts.

I think that the best way to improove this kind of card is to make them summon another rare.

Or perhaps have it summon the Uncommon equivalent that increases the same facility.

Yes but it sounds like a dead draw. maybe "replace selected card in hand with master bricklayer" is better

Yeah, I could go for that instead.

Ehm, it should be
Quarry:+1
Replace a card in hand with Master bricklayer

(you forgot the quarry+1 in your edit)