Undertale Adventures X: How to Evo Summon Mythic Units (2026 Guide)

If you have watched a squad melt a late chapter boss in seconds, you have probably asked the same question everyone asks: how do you evo summon mythic units in Undertale Adventures X? The answer is not one button — it is a short chain of steps that most players skip, and skipping them is why their summons feel weak. Undertale Adventures X is a Roblox tower defense game where your units are your entire strategy, so understanding evolution and summoning is the difference between replaying chapters and clearing them first try.

This guide breaks the process into plain steps: what the requirements actually are, where Souls and Soul Fragments come from, how Trait Rerolls fit in, and how to avoid the traps that waste your rarest materials.

What "Evo Summon" Actually Means in Undertale Adventures X

The phrase "evo summon" blends two separate systems, and mixing them up is the first mistake new players make.

• Summoning is how you obtain new units. You spend Souls at the summon area, and the game rolls a unit based on rarity odds. Soul Fragments are combined into Souls before you can summon.
• Evolving is how you upgrade a unit you already own into a stronger form. This usually requires a maxed-level unit, specific evolution materials, and sometimes a duplicate.

A "mythic evo summon" is therefore the end result: a unit that sits at the top of the rarity ladder and has been pushed into its evolved form. You do not summon a finished mythic out of thin air — you either pull one at mythic rarity and evolve it, or evolve a strong unit until it reaches that tier.

Understanding the rarity ladder

Rarity determines the ceiling of a unit, but evolution determines how close you get to it. Exact odds shift with every balance patch, so treat the table below as a general map rather than a fixed drop-rate chart.

Because Side Productions tunes the game regularly, always confirm a unit's evolution path in the in-game index before you dump materials into it.

Before You Try to Evo Summon Mythic Units: The Checklist

Most failed attempts are not bad luck — they are missing prerequisites. Run through this list before you touch the summon or evolution screen.

1. Unit at max level. Evolution almost always requires the base unit to be fully leveled first.
2. Evolution materials collected. These drop from specific chapters and events, so farm the stage that lists them as a reward.
3. Enough Souls or Soul Fragments. You need a buffer for the summon itself and for any follow-up upgrades.
4. Duplicate or alternate requirement met. Some paths ask for a second copy of the unit rather than materials.
5. Chapter progress unlocked. Certain evolution stations and stages only open after you clear specific chapters.
6. Trait Rerolls on hand. Not required to evolve, but evolving a badly traited unit wastes the boost.

Step-by-Step: How to Evo Summon Mythic Units in Undertale Adventures X

Here is the practical order of operations. Doing these out of sequence is the fastest way to burn materials for nothing.

1. Pick your target. Choose one unit with a known evolution path rather than evolving whatever you pulled last.
2. Level it to the cap. Feed it experience through chapters or training until the game shows the evolution option as available.
3. Farm the evolution stage. Look at the unit's evolution requirements and run the exact chapter listed. Do not guess.
4. Bank your Souls. Combine Soul Fragments into Souls and hold a reserve — summoning and upgrading compete for the same pool.
5. Evolve the unit. Open the unit menu, confirm the materials, and trigger the evolution. The stat jump is immediate.
6. Reroll the trait afterward. Use Trait Rerolls in the upgrades area to chase a trait that matches the unit's role — damage, cooldown, or range depending on its kit.
7. Test in a real chapter. Run a stage you previously struggled with. If clear speed barely changes, your problem is team composition, not the unit.

Souls, Fragments, and Rerolls: Funding Your Mythic Summons

The economy behind an evo summon in Undertale Adventures X is simpler than it looks once you separate the currencies.

Soul Fragments are the raw material. They combine into Souls, and Souls are the currency you actually spend to summon units. Trait Rerolls are a separate resource used in the upgrades area to buff your team's stats — they do not summon anything, but they decide whether your evolved unit performs at its potential. Gaster Hands appear as a reward from certain promotions and events and are worth saving for high-value targets.

One underrated source of all three is the code system. Codes are redeemed through the Codes button on the right-hand side of the main lobby: enter the code, then press Enter on keyboard, A on Xbox, X on PlayStation, or simply tap outside the box on mobile. At the time of writing, the active code grants a bundle of Trait Rerolls, Gaster Hands, and Souls — exactly the resources an evolution project needs. For the current live list, check the Undertale Adventures X codes guide on GamesRadar, since codes in this game can expire within hours.

Mistakes That Stall Your First Mythic Evolution

Community reports and player experience point to the same handful of errors over and over. Fix these and your progression speeds up noticeably.

A quick prioritization rule

If you are unsure what to do next, ask which action moves your team forward rather than your collection. Evolving one unit that fixes a hole in your defense beats evolving three units that duplicate a role you already cover.

FAQ

How do I evo summon mythic units in Undertale Adventures X as a new player? Focus on one unit. Level it to the cap, farm its listed evolution stage, and only then spend Souls. New players rarely fail because of luck — they fail because they spread limited materials across too many units.

Do codes actually help with mythic evolutions? Yes, indirectly. Codes hand out Souls, Trait Rerolls, and Gaster Hands, which are the exact resources you need to summon candidates and polish them afterward. Codes expire quickly in this game, so redeem them as soon as you see them.

Do I need a duplicate of a unit to evolve it? It depends on the unit. Some evolution paths require a duplicate, while others ask only for materials and a maxed level. Check the in-game index for your specific unit before you spend anything.

What is the fastest route to more Souls? Combine Soul Fragments consistently, clear the highest chapter you can finish without failing, and redeem every active code. Stacking those three sources is far faster than grinding a single low-level stage repeatedly.

Getting your first evolved mythic is a milestone, but the habit matters more than the unit. Pick a target, meet every requirement before you spend, evolve before you reroll, and keep your Soul reserve topped up through codes and steady chapter clears. Do that, and knowing how to evo summon mythic units in Undertale Adventures X stops being a mystery and becomes a routine you can repeat for every new unit that joins your roster.