Your first objective is not the rarest possible unit. It is a team that can start a match cheaply, clear groups, and survive long enough to upgrade a real carry. Once that loop is stable, every code, box, and lucky roll becomes more valuable.
First-session route
Placement basics
Use a turn, loop, or long shared lane where possible. The opener protects the early game; it does not need every upgrade. Save for the unit that clears most enemies, then bring a boss option online before the durable target arrives. Support comes after the carry, because a buff with nothing strong to amplify is wasted currency.
Roll and resource discipline
Set a stop rule before opening boxes or rerolling traits. Lock units you want to test. Keep enough Crystals for a known next step, and compare a new pull on the same stage before investing deeply. Luck changes what you receive; it does not replace a balanced lineup.
Beginner video
This recent progression video is useful for seeing the menus and general flow. Treat its unit choices and numbers as one player's build, then compare them with your current server.
Quick answers
What should I upgrade first?
Upgrade the unit currently stopping the most enemies. If you lose before placing it, fix the opener or cost problem first.
Should I reroll a trait immediately?
Only on a unit you have tested and plan to keep. Early filler units should not consume your rarest resources.
Are Gems the main currency?
Current Anime RNG Defense code rewards are described as Crystals, not Gems. “Gems” often appears in results for a different anime defense game.