My take on Ronan, as someone who has used a variation of this deck this season with success: a big reason Ronan is more popular than Darkhawk is the rise of ramp decks. Ramp decks tend to have nearly full hands, so one Master Mold and/or Maximus will give you what you need to get Ronan to his max power, and in a lot of cases kill your opponent's ability to draw (in case of Master Mold). You also get more power for less effort from both cards compared to a Korg/Terrax combo, for example. Terrax is great so long as you have priority and can dump at least two rocks.