Universal Tower Defense Z, unit by unit.

On 9 July 2026, Update 4.0 renamed Universal Tower Defense X to Universal Tower Defense Z. That is the whole event, and it has caused more confusion than anything else this game has done. It is the same Roblox experience, place ID 133410800847665, run by the same group. Nothing was reset, nothing was migrated, and there is no second game to go and join. If you had X favourited, the thing in your favourites is Z. Your units, your gems and your redeem history came with you, which is also why an old X code that fails today failed because it expired, not because the rename invalidated it.

What genuinely changed is the top of the roster. Nineteen units sit at S+ after 4.0, and the update brought a wave of crossover arrivals with it: Human Spider, Iron Billionaire and Symbiotic Alien from the Marvel side, Trickster, Anne, Feline and Cranium from the Persona set, and Bleach content including Flame Captain, Ice Queen and The Almighty King. If you stopped playing before 4.0 and came back, the tier list you remember is the wrong one, and it is wrong at exactly the end that decides where your shards go.

The practical consequence for a returning player is narrow but real. Do not spend on the unit that used to be best. Read the current tier list, check whether what you already own has a documented Synchro partner, and only then start committing Etherealization shards, which are the one resource in this game you cannot get back.

Synchro is the mechanic people ask about most, and it is the one the internet is least reliable on. Start with the vocabulary, since most guides get that wrong first. Pro Game Guides distinguishes a Synchro Clash, where both units stay on the board and fire a combined attack, from a Synchro Drive. Separately, some pairings merge two units into one. No source calls any Synchro type a "Fuse". Across Pro Game Guides and Deltia's Gaming, 7 pairings are documented.

A Clash has conditions, and both sources agree on them, which makes this the best-corroborated thing on the site:

• Both units must be placed on the same field.
• They must be within each other’s attack range.
• Both must be fully upgraded, or at least upgraded equally.
• The clash then fires automatically, with no button to press.

Two Clashes have published numbers, and they are not close to each other, which is exactly why we attribute each rather than averaging them into one tidy claim.

• Mimicry Sorcerer (Cursed Love) + Jane Juliet (Larper): 500% of the average damage between the two units, on a 60 seconds cooldown, attack type Water (Ground). Source: Deltia's Gaming.
• Pirate King (Voyage) + Quake Warlord (Destroyer): Hits the entire map for massive averaged damage, on a 300 seconds cooldown. Source: Pro Game Guides.

One merge has a name behind it. Pro Game Guides says Limit Breaker Prince can Synchro with Goku into Vegito Super. It also notes that Human Spider's two merges inherit his Trait and stats, so how you build him decides how hard they hit. For the other merges, the sources document the pairing but never name the resulting unit, and neither do we.

Not verified yet. This site used to claim nine Synchro pairs in two kinds, one of which it called a "Fuse", and it printed a name for every merged unit: Symbiote Spider, Mechanical Spider, Unparalleled Armor, Majestic Armor, Underworld God (Synchro), Revolutionary Chief (Spade). The pairings were mostly real. The names were not. No source names those units, and one that we did print, "Fused Warrior (Super)", is a real merge under the wrong name: Pro Game Guides calls it Vegito Super. A result name is the thing a player farms toward for a fortnight, so a wrong one is worse than none. Two further pairs we published, Nutaru with Sasku and Underworld God with Water God, appear in no source at all and are gone.

Look at a unit called Ice Queen (White Haze), or Visionary (Unrivaled), or Trickster (Phantom). Guides routinely read that bracket as a rarity band, as though Unrivaled were a tier above Phantom. It is not. The bracket is the unit's evolution stage: what it became after you evolved it. Rarity is a different property that the game tracks in its own field, and the two move independently. A high-rarity unit can sit unevolved and a low-rarity unit can be fully evolved, which makes them completely different investments.

This matters because it changes what you go looking for. If you think the bracket is the rarity, you will chase evolution stages you cannot reach and ignore units whose ceiling is higher than their current label suggests. The bracket tells you what a unit is right now. Rarity tells you what it is, permanently.

Rarity is a real, separate field, and Pro Game Guides' unlock table carries it in its own column. The values that appear in it are Mythic, Legendary, Epic, Rare, Secret, Exclusive. Mythic is far and away the most common label in that table, and a good number of rows simply read "Rarity TBA", which is the table's own way of admitting it does not know yet.

Not verified yet. We have not transcribed that column row by row, so this site does not show a rarity on each unit page. A per-unit rarity we had filled in for some units and guessed for the rest would be worse than none, because you could not tell which was which.

There are 9 codes on the codes page, and a code gets there only when at least two independent trackers list it as working. We read Pro Game Guides, Destructoid, Beebom and Try Hard Guides, compare them, and publish the overlap. Each row names the trackers standing behind it, because a code four trackers agree on is a safer paste than a code two agree on and you should be able to see that difference rather than have it averaged away.

The rule has an obvious cost. Try Hard Guides currently lists around twenty active codes; Pro Game Guides, Destructoid and Beebom each list seven. Where they disagree, the code stays off our active table. A longer list is easy to produce and looks more authoritative, and it is also how you end up pasting fifteen dead strings in a row and concluding that the redeem box is broken. The redeem box is fine. The list was old.

Redeeming is the easy part: the Codes button sits on the right-hand side of the screen, and the two things people get wrong are dropping the trailing exclamation mark and retyping the capitals from memory. Every code on our table is a tap-to-copy button for exactly that reason.