Its comparable to Gilded Lotus, and its arguably more powerful as it makes 5 mana in a mix of colors rather than just 3 in a single color
Its a card that brings nothing but value to your side of the table
In more than one in eight draft boosters you won't find a rare, but a mythic rare
Since your opponent can make use of the ink before you (since they come into play exerted) you need to make sure you are using this against decks unlikely to take advantage of the free ramping, whereas your deck is obviously built to take advantage of it
In comparison to the sapient mice, squirrels, and other denizens of the Valley, calamity beasts are absolutely enormous
Now to be fair I do run a creatureless Zur deck designed for higher table play for punishing nasty players here (Zur's Overburdening Commander Deck | Article by Abe Sargent (coolstuffinc.com))