When progress slows in Mythos Slayer, the useful comparison is what your next purchase adds for its price. A new unit, an upgrade to one you own and a hero upgrade all use the same gold. Their benefits depend on your current levels.
Correction: an earlier version of this guide treated the advanced dragons' three visible projectiles as three damage hits. The current game applies damage once per volley. It also does not let you buy unlimited copies of the same unit: each type is recruited once and then upgraded.
Compare an upgrade with a new recruit
At base level, a Swordsman costs 80 gold and deals 2 damage per second. Its first upgrade costs 144 gold and raises its damage from 2 to 3.8, before attack-speed bonuses. That is 1.8 additional DPS for 144 gold. A Dwarf Warrior costs 280 gold and adds 4 base DPS. For this particular comparison, the upgrade costs 80 gold per additional DPS; the recruit costs 70. The cheaper button and the more efficient button are different.
This example assumes both purchases are available, no Gale Blessing levels, and no awakening bonus. The recruit list unlocks in order. Check the next available card rather than assuming you can skip directly to a late unit.
Why an old unit can become useful again
A unit's damage uses its base damage multiplied by 1 + 0.9 times its level. Each 50-level milestone multiplies this by another 50. Upgrade prices grow by 1.38 per level. These milestones mean a base-recruitment table alone cannot tell you what to buy in a developed save.
For example, a level-49 Swordsman has a damage factor of 45.1. At level 50 the factor becomes 46 × 50, or 2,300. The damage jump is large, but reaching that level has a cost. Compare the milestone price with other upgrades you can actually afford.
Visible projectiles do not multiply the damage
| Unit | Recruitment price | Base DPS |
|---|---|---|
| Archangel | 40 billion | 125,000 |
| Ancient Jade Dragon | 200 billion | about 444,444 |
| Awakened Crimson Dragon | 1 trillion | about 1,666,667 |
| Seraph | 5 trillion | 6,000,000 |
These figures are damage divided by the base attack interval, at unit level zero with no speed upgrades. The advanced dragons launch three visual projectiles, but that is not a reason to triple these rates. Animation and overkill can also make short observed fights differ from a theoretical DPS rate.
Evaluate Rebirth as a time trade-off
After clearing Boss 10, Rebirth resets your purchases and applies a factor of 1 + 0.4 times the highest boss cleared in the current cycle. It multiplies the permanent bonus you already have. A first reset at Boss 10 gives ×5. Another reset there changes ×5 to ×25. Resetting at Boss 20 gives a factor of ×9 instead.
Going deeper earns a larger factor but delays the next run. The formula does not establish a universally optimal reset point. Consider how long the next boss will take and whether a nearby unit milestone can help. The Rebirth button shows your current bonus and the proposed result.
Rebirth preserves the boss cycle. If you have entered cycle 2, resetting does not return enemy health to cycle 1. Review that choice before moving beyond Boss 40.
Play Mythos Slayer and see the controls. The calculations above use the public game's source, including unitDmg, unitIv, unitUpgCost, doUnitVolley and prestigeFactor.