Forget chasing the monthly Legendary Fusion (which requires 20,000+ energy). As a free player, look for (like Gnut or Emic). You can usually complete these with 2,000 gems and rigorous daily logins. Fusions are for whales; Fragments are for grinders.
Even if you lose, the Bazaar allows you to buy Drextar Bloodtwin fragments—one of the best free Legendaries in the game. Final Thought free account raid shadow legends