The systems that decide your damage

Every unit you pull is a base version of itself. It has a level, it has whatever traits and relics rolled onto it, and it has a name with no bracket after it. Three separate systems change that unit, and it helps to know what each one is actually for before you spend anything.

Level is the XP layer. Units gain XP by being placed in runs and surviving them, so levelling is a by-product of playing the modes you were going to play anyway. It costs no premium currency. This matters more than it sounds, because it makes levelling the only free layer in the game, and free layers should always be exhausted first.

Etherealize consumes Etherealization Shards. It is the paid power layer, the one where a unit stops being a body on the board and starts carrying a wave. Shards do not come back. There is no refund, no unequip, no way to strip an etherealized unit and get the material out. Everything about how you should approach this system follows from that single fact.

Evolve is the transformation. It turns a unit into a new named variant with new art, and that variant name is what shows up in brackets on tier lists. Evolving is the top of the stack, not a shortcut around it.

Community consensus, and it is unusually consistent for a Roblox tower defense community, is level before you reroll heavily and level before you etherealize. The reasoning is not mystical. Levelling is free and reversible in the only sense that matters, which is that it never punishes you. Everything else in the stack is a one-way door.

The failure case looks like this. A player pulls a unit that is sitting high on a tier list, immediately dumps shards into it, spends forty trait rerolls chasing a good roll, and then finds out two days later that the unit is a specialist they cannot fit into their team. The shards are gone. The tokens are gone. The unit is on the bench. Meanwhile the unit they actually field every run is still sitting at a level they never bothered to push, and that unit is the one failing the wave.

A workable rule: a unit earns your shards by surviving your rotation for a week, not by surviving a tier list. Play it, level it, watch whether you keep picking it when you are not thinking about it. That is the unit worth investing in.

The second half of the ordering rule is that Evolve comes last. Evolving does not skip the levelling requirement and it does not refund the etherealize step. It is the capstone. Players who read the bracket labels as rarity tiers sometimes reach for Evolve first, expecting it to promote a unit into a better rarity. It does not touch rarity at all. Rarity is a separate, fixed property. What Evolve changes is the evolution stage, and that stage is what gates a Synchro pairing, which is a much better reason to care about it.

A unit carries two descriptors, and guides routinely mash them into one column.

• Evolution stage. The bracket after the name. Human Spider (Responsible). Symbiotic Alien (Apex). Iron Billionaire (Genius). It tells you which version of that character you are holding, and it is something you do to a unit through the Evolve system.
• Rarity. A separate property with its own values (Mythic, Legendary, Epic, Secret, Exclusive). It is fixed by what the unit is, and it is the field that appears as a Rarity column in unlock tables.

So Ascension is not a rarity and Mythic is not an evolution. When a guide writes that Ascension is the highest rarity, it has taken a word from one field and filed it under the other, and the summoning and shard advice built on top of that is unsound.

This is not pedantry. It has teeth. Every one of the 9 confirmed Synchro pairs names a specific evolution stage, so a player who reads brackets as rarity has no reason to care which version of Human Spider they are holding, and will miss the fusion entirely. The Evolve page pulls the two fields apart properly, including every bracket label that actually appears on the roster.

Traits and Relics both roll onto a unit and both can be rerolled, but they draw on separate token stocks. Traits use Trait Rerolls. The stat side uses Stat Rerolls, also called Relic Rerolls depending on where you read it. Running dry on one does not lock you out of the other, which is the single most useful thing to know about them, because it means you can keep working on a unit even when one token type is at zero.

The trap in both systems is the same and it is psychological rather than mechanical. Rerolling is fast, it is satisfying, and there is always one more roll. Set a budget before you open the panel. If you cannot say out loud how many tokens you are willing to spend on this unit right now, you are not rerolling, you are gambling with a currency you will want back later.

Update 4.0 added Synchro. Field two specific units together and something happens. It is a team-composition system rather than an upgrade system, which is why it sits apart from the three-layer stack, and it is the only power increase in the game that costs no currency at all.

What almost nobody documents is that Synchro is two mechanics. Fuse merges the two units into a brand new unit, so your two towers become one. Clash merges nothing: both towers stay on the board and run a combo attack while both are in range. That distinction changes your board count, your positioning and your shard planning.

9 pairs are confirmed, 7 Fuse and 2 Clash. Human Spider (Responsible) and Nutaru (Beast) each anchor two Fuse pairs, so owning either gives you a real choice about which fusion you want. The full list, the two-kind split, and the test protocol we want you to run are on the Synchro page.