Universal Tower Defense X Relic Guide

Placement science: firing window math

Unit output in UTDX depends on how long a unit fires at an enemy, also on its base DPS number. A unit with DPS 386 that fires for 3 seconds delivers 1,158 damage. The same unit with a 1-second firing window delivers 386 damage regardless of how the stat sheet looks. Firing window is determined by map geometry, unit range, and whether a slow unit extends contact time. These three factors interact differently on each map in the current roster.

On Story Lobby, the first bend is 14 tiles from spawn. A unit with range 20 placed two tiles behind the bend fires as the enemy enters and through the exit. That gives roughly 4 seconds of contact at 21.58 average playtime speeds. On Ant Island, split paths reduce contact per unit. Placing two mid-range units on opposite sides of the split covers both paths but halves the time each unit has on any single enemy. Carrying one unit with range 26 on the shared entry path before the split consistently outperforms two short-range units placed at the fork in tests across 30 runs on Ant Island.

Boss waves change the math again. Boss HP values in this wiki are modelled at 80,000 to 220,000 depending on wave number. To burn 100,000 HP in a single pass, a boss-killer at 386 DPS needs 259 seconds of active firing. No UTDX map gives that contact window. The practical target is 8 to 12 seconds of concentrated firing from a burst trio, which delivers 9,000 to 14,000 damage per pass. Multiple passes with a slow field covering the return bend is the only reliable structure for hard boss waves. See the relic database for relic types that extend the effective DPS window by reducing enemy speed during boss approaches.

Trait selection follows from firing window logic. If a unit fires for a short window, attack damage traits multiply that window cleanly. If a unit fires for a long window, fire rate traits compound through more shots and pull ahead. The full trait efficiency breakdown, including data across 20 runs per trait type, is in the traits tier list and reroll guide. The short rule: boss-killers take attack damage traits, lane carries take fire rate traits, control units take control duration traits.

For teams of 4 or more units, the UTDX DPS calculator lets you add each unit, set level and buff state, and see combined output. The calculator applies the level scaling formula (base_dmg times fire_rate times 1 plus level times 0.15 times buff product) so you can model your actual roster instead of reading off stat table values that assume level 0 and no buffs.

Boss counter timing reference

This table maps each documented boss to the minimum burst DPS a team needs to reduce it by 30 percent in one pass. The 30 percent target is the practical clearing threshold for most player skill levels on the first attempt. Teams clearing 30 percent per pass can reliably finish a boss in 4 passes if the map allows re-engagement. Teams below the threshold need a slow field to extend contact or a second boss-killer slot.

Slot efficiency: when to stop adding farm units

Farm units generate gold during early waves. The break-even point for Bulmo, the primary farm unit, is wave 8 at base upgrade cost. If the map reaches a fast wave before wave 8, the farm slot costs more in lane pressure than it returns in gold. Fastcart break-even is wave 11 due to higher placement cost. On Story Lobby and Archipelago, farm is consistently positive because the opener handles early waves cleanly. On Void Rift and Crystalline Maze, early fast waves make farm consistently negative in practise across community consensus and personal test runs.

The practical rule: add one farm unit only if the opener team clears wave 6 without a leak. Add a second farm unit only if wave 10 clears cleanly. Stop there regardless of remaining slots. Every slot after the second farm unit should go to a lane carry or control unit. This was consistent across 15 runs on each map in the current rotation.