If you do, Furyblade Vampire gets +3/+0 until end of turn
If the player times using Cyrus right, they can make sure they gain a point, which can make the difference and potentially win the player the game
In the absence of Earthen Vessel, Firebreather can offer a huge advantage to fire decks who will essentially have all the energies they need from playing this card just once
Having them at 2 Life Cards means they won't gain a Life Card from OP04-112-yamato, won't gain Rush on OP07-119-portgasdace, and will have to trash a Life card if they play EB01-059-kingdom-come
Malevolent Rumble Malevolent Rumble stands out among greens other mill cantrips because of the value represented by its Eldrazi Spawn token
Its a symmetrical effect, however, but you can get around that by running snow-covered basics: they have a different name to their non-Snow counterparts, so only the snow-covered versions will benefit