CardName: Court of Awakening
Cost:
Type: Land
Pow/Tgh: /
Rules Text: {t}: Add {1} to your mana pool.
{1}{gw}, {T}: Untap target creature.
Flavour Text:
Set/Rarity: Multiverse Design Challenge Uncommon
Court of Awakening
U
Land
: Add to your mana pool.
, : Untap target creature.
LOL. That's perfect, it directly answers Rubinia, and could easily go into any deck. It might need to cost more on a land, because repeatable "untap" could be very useful on your creatures, but it should work nearly as well as an answer.
It is cheap, but untapping comes pretty cheaply sometimes. Look at Kiora's Follower. But you're right, it would probably be overcosted because it's a land.
: Add 
to your mana pool.
,
See Challenge # 105. I rolled Rubinia Soulsinger.
LOL. That's perfect, it directly answers Rubinia, and could easily go into any deck. It might need to cost more on a land, because repeatable "untap" could be very useful on your creatures, but it should work nearly as well as an answer.
It is cheap, but untapping comes pretty cheaply sometimes. Look at Kiora's Follower. But you're right, it would probably be overcosted because it's a land.
Wirewood Lodge was what was sticking out in my mind. Though, I don't really think knowing that card exists helps one way or the other.
I'm not the best judge of power, so I can't offer further comment on whether this is too strong for the cost or not.