Drop that to one mana each, two total with Heartstone or Training Grounds
Popular sets include Scarlet & Violet, Crown Zenith, and 151
Like most Magic: The Gathering cards, the value of Liberator, Urza's Battlethopter depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (The Brothers' War)
Your win conditions are likely to be either swinging at your opponents with buff Merfolk until their life total hits zero, or you can try to sneakily win using Simic Ascendency , which wins you the game once it hits 20 counters
There is a small chance that one of your Common or Uncommon cards can be replaced with a card of a higher rarity