Don't suspend it--Reshape it or Whir of Invention, for x=0 in both cases. You could always Kari Zev's Expertise it. Of course, there are the other usual methods for casting cards without paying their mana costs but we aren't going to list all of them here.
In modern, well, 5 mana is quite a lot and theres so much crazy hate around and then it doesnt just flat out win and you cant "blink" it ... so yea, its just a nice Limited card sadly ...
Oh, I did not say that anyone would be playing it; rather, I noted only that for 3 colors that is what one could get for playing it. It won't even show up in vampire tribal. I concur, though--very solid uncommon for Limited.
So we finally get to meet Captain Vance? It's about time. Are there any low-curve red decks that can cast three spells in one turn? (rhetorical question--you need not answer)
Acorns are Food for squirrels. If the spring and summer have been good for plants, the squirrels might get to collect a Second Harvest before winter sets in.
Oh, I did not say that anyone would be playing it; rather, I noted only that for 3 colors that is what one could get for playing it. It won't even show up in vampire tribal. I concur, though--very solid uncommon for Limited.
So, for 1 more mana Siege Rhino is now a 5/5 and a vampire.
This might make Storm the Vault a possibility worth considering.
...and it is a courier.