This has potential as a red aggro 2 drop that is a decent mana sink / strong mono red build-around. Most 2 drops with haste for 2 mana have 2 power, so this has higher damage potential on turn 2 and ties your typical 2/X with haste in 2 attacks for a total of 4 damage. This makes all your Rabblemaster variants particularly deadly, especially Squee. Being able to create pseudo Hellspark Elementals late in the game is also nice.
This does have a lot of competition with the other 2 drops with haste though since things like Earthshaker Khenra / Robber of the Rich / Bloodthirsty Adversary all have abilities that scale well in the late game too while not forcing you to commit to mono / heavy red to really achieve their maximum potential. This probably has the highest ceiling of any aggressive red 2 drop, and the floor is probably better than most other than trading with a 1/1.
I like this card as a buildaround +2/+0 lord focused on "haste matters." 36/540 cards in my cube say "haste" (including noncreature cards like Rhythm of the Wild, which seems spicy with Ardoz). I like the sound of turn 1 Kumano Faces Kakkazan, turn 2 Ardoz, turn 3 Squee, Dubious Monarch. Ardoz is also pretty good on its own as a 1R 3/1 haste on turn 2, or it's OK as a late game mana sink for board stalls. On the other hand, this is not a 3/1 forever, so it might seem a bit anemic as a 1/1 if you don't have other haste creatures/tokens in your deck -- that's why I think it's a haste buildaround.
Card looks sweet. Red 2s for us are always weird since most of them are pretty middling and boring from a powerlevel perspective. Excited that this gives some interesting and potentially powerful token incentives for red aggro and faster midrange decks. Playing this on 6 can also be pretty decent topdeck. The mana sink aspect of this especially gives plenty of late game reach, and while not so much to block with it can still set up some slower wins with Opposition or Garruk Wildspeaker.
It might be a hot take, but personally I think this is better than Kari Zev, Eidolon or Dire Fleet Daredevil.
This can attack as a 3/1 haste for 2 which is exactly what red aggro wants to do, and in the right deck it shouldn't be hard to trigger the activation at least once a turn.
If you follow this up with a T3 Rabblemaster variant you can really go nuts because then you get two activations, which means it can add 6 power on turn 3. Seems good.
It will depend on how much other haste is in the cube I think. Over 2 turns this has the same damage output as any other 2 power haster and 2 drop haste with late game value is pretty common (Earthshaker Kenra, Robber of the Rich, Bloodthirsty Adversary) and that's not even going in to reds 2 drops without haste. I just see too often the opponent having an x/2 and this thing no longer swinging because of it.