The idea is similar to Desert Obelisk. The stats are just good, so it isn't completely useless, and the effect kicks in with just one more on the field, but I don't think it will be played much, if at all, outside of arena. It's too difficult to make it work, and not really worth it either, I think.
One single discount on rhino and 3 of those is lethal. And you can draw 3 of these and/or Rhino easily with Hunter's Call. This will be fun in Wild, and I will reach legend with this. People comparing with desert obelisk aren't even close.
As another one pointed out already, this is the Desert Obelisk of this expansion. Most of the time this is a vanilla 3/4 beast.
It's way, way better than Desert Obelisk. And a Vanilla 3/4 beast is honestly not a bad card to have. Not especially good, but it has a good backup state if you need it. Which Desert Obelisk does not. Also having two 6/4s for 3 each is a much better situation than two Desert Obelisks.
Hunter has so many ways to copy this minion, that I think there might be a fun deck you can run there. Dunno what that'll look like at this point.
I just can't believe people are seriously comparing 3 mana 3/4 to a 5 mana 0/5. There are so many ways to make these 6/4 for 3 and even ways to otk with them without running awful combo cards. Worst case it's still a 3 mana 3/4 beast.