Secret units are the crown jewels of Universal Tower Defense — powerful, game-changing, and often hard to get. If you want a clean roadmap for every secret available at launch (Sun Jin Woo, Ragna, and Lelouch), this guide tells you exactly where to go, what to do, and smart shortcuts to finish the tasks faster.
I’ll also include practical tips for evolutions, pity mechanics, and the annoying placement/macro parts so you don’t waste time. Also check out our Universal Tower Defense Codes & Tier List for more rewards!
1. Sun Jin Woo — The easiest secret
How to get him
- Reach Level 10 (you can’t pull him before level 10).
- Open the banner (index) — Sun Jin Woo is on the pull banner. According to early data, his base pull chance is extremely low, so plan your gem usage (don’t blow everything before level 10).
Evolution / dupes
- Evolution items are craftable: you can make the required mats instead of hunting random drops. That makes evolving him straightforward once you have the materials and gold.
- Etherealizing (getting dupes) is the hard part — secret units are rare, so expect slow progress toward full etherealization.
Quick tips
- If you want a fair shot, wait until you’re at least level 10 and have some accumulation of rerolls/gems.
- Save pulls for banner events that boost pity or give free rerolls if they appear.
2. Ragna — Challenge drop (2% drop with pity)
How to get him
- Go to the Play area in the lobby and immediately head left to the Featured Challenges section.
- Find Ragna Crimson (featured challenge) and enter it.
- Beat the challenge: Ragna has a ~2% drop rate and there is usually a pity system (about 75 runs pity noted by players).
Notes on difficulty
- The Ragna challenge is heavy on HP and mechanics. It’s easiest with a coordinated group or a high-DPS lineup if you want to solo.
- If you plan to grind for pity, running the challenge repeatedly with a small, repeatable team is the fastest route.
Evolution
- Ragna’s evolution follows normal crafting/evolution rules — gather the listed items and gold. No special hidden steps beyond the normal evolution system.
Quick tips
- Group up if the challenge feels unwinnable solo — co-op makes the runs much faster.
- Set a consistent team composition to speed up clears and reduce mistakes.
3. Lelouch — Secret quest line (Power of Kings)
Lelouch is obtained via a multi-step quest chain called Power of Kings. This is the most involved route but it rewards a secret unit plus a large number of rerolls/gems along the way.
1. Reach Level 30
- Unlock the quest in the Quest → Personal → Power of Kings slot.
2. Talk to the Distressed Subject (lobby NPC)
- Walk the lobby and find the NPC with a red marker/triangle above their head. The distressed NPC is random (examples: Naruto, Zoro, Rukia, Shanks).
- Interact and skip dialogue to complete.
3. Find the Correct Board Game (chess board)
The map you need depends on the NPC’s anime origin:
- Naruto NPC → Ninja Forest (act 1 recommended)
- One Piece NPC → Marine Base
- Bleach NPC → Hollowed Moon
In that map, search for the small chessboards scattered around (usually 3–4). Only one board triggers the chess minigame. Step on boards until the chess match UI appears. The chess minigame choices are not random per board — each board uses a fixed choice path for that map. Follow the same option sequence each time to win.
4. Talk to the Mysterious Woman
Return to the lobby (Play & Extras area) and speak to the woman near the group rewards section.
5. Complete 80 Waves in a Single Run
This must be one run (so use Infinite Mode). Reach wave 80 and then return to lobby to claim the quest.
6. Kill 15 Boss Enemies
Use Infinite Mode, start the map and kill the first boss (they spawn under certain waves). Repeat runs until you reach 15 boss kills. Fast method: run short infinite cycles and rejoin to spawn the boss more often.
7. Upgrade Relics 75 Times (resource-efficient method)
- The quest counts individual single-level upgrades, not “max” upgrades.
- Method: pick low-level relics and press Enhance (+1) repeatedly across many relics to reach 75 single-level upgrades. This saves huge amounts of gold vs hitting “Max”.
- Tip: don’t accidentally use the “Max” button — it counts as one upgrade even if it raises many levels.
8. Place Any Unit 5,000 Times (macro method)
- Easiest solution: use a cheap farm unit (Speedwagon / Speedcart) and a simple macro tool (e.g., TinyTask).
- Loop: place Speedwagon → sell → repeat. Each placement counts.
- Make sure to close the result/replay UI the right way (if you lose purposely, close the result tab with the X instead of pressing Replay) so your macro can loop cleanly.
Getting all secrets in Universal Tower Defense is totally doable with clear targets and repeatable methods: pull for Sun Jin Woo once you hit level 10, grind the Ragna challenge for pity and drops, and work through the Power of Kings quest line for Lelouch (use the single-level relic trick and a placement macro to speed the final steps). Finish these three and you’ll own the game’s major secret units — the rest is just optimizing relics and chasing dupes. Good luck, and enjoy the hunt.