Upgrades In-Depth: More Than A Tooltip

So I started playing a few days ago at a friend's suggestion, and once it got me hooked I started getting curious about the mechanic interactions that aren't quite clear from tooltips or the help section. So, I did some testing of my own! And now I'm here to share my findings with the world. I'll go mechanic by mechanic and give each two paragraphs; the first will go into the deep mechanics and the second will sum it up with why the findings are interesting or unexpected. If you've got questions, comments, or your own findings, I'd love to see them in the comments!

• Damage Multiplication: All different sources of multiplier stack multiplicatively. No multiplier on damage improves the direct damage from anything but bullets.

This is probably the most important thing i've found for maximizing DPS so it's first on the list. Every non-bullet damage source and every damage multiplier I tested all showed the same conclusion. This means if you want to put points into shot damage, you should make it your primary damage source and not bother with things like nova damage or reflection, and vice versa, if you don't make shot damage your primary damage source you can save money by avoiding multipliers

Here's all the different multipliers and damage sources I tested, for completeness' sake Multipliers: Incineration, Shatter, % Bonus Damage Vs Element, % Bonus Damage Vs Enemy Type, Execution Indirect damage: Fire, Darkness, Nature, Electricity, Reflection

• Fire: Applies an effect on enemies that multiplies damage taken (based on incinerate's level) and deals damage over time. The effect lasts 5 seconds, and deals damage once per second starting 1 second after it's first applied. The damage instance interval on an enemy is set when that enemy is first ignited: each further instance of fire will reset the burn timer to 5 seconds but not affect the damage timer. The amount of damage fire does per second is based on the most recent source of fire: 0.05% of enemy maximum health for the fire aura or 50% of final shot damage for fire shots.

So I mentioned how no indirect source of damage is boosted by multipliers, but fire is kind of an exception. Like I said, fire damage is based on the most recent fire source. If you ignite an enemy with a fire shot, they catch fire after the damage so incinerate doesn't affect that shot. If you hit them with another fire shot while they're burning, incinerate WILL affect it, and fire damage will be calculated from that multiplied shot instead of the first one. One last note: the "most recent fire source" thing means fire aura is almost nullified by fire shots and good bullet output because you'll almost certainly hit every enemy at least once between the aura pulse and the fire tick.

• Ice: Slows an enemy and applies an effect that multiplies damage taken based on the level of shatter. Ice slows enemies based on their current (not maximum) movement speed, 25% for ice shots and 40% for ice pulses. This slow can be applied again and again, but can not bring movement speed below 0.25. Both the slowing effect and the shatter effect are permanent.

Like with fire, ice shots apply freezing after their damage, so the first shot is not multiplied by shatter. Other than that, there's not much to say, since its usefulness is still obvious. Max it and be untouchable for a good long while, hooray!

• Earth: Stuns a non-boss enemy. Shots stun for about 0.5 seconds and aura pulses sun for about 0.25

First and most important thing: stun duration is currently bugged. Buying more doesn't actually make the stuns any longer, on either the shots or the aura. Even so, this is a damn useful ability solely because it stops assassins in their tracks: if an assassin is stunned while leaping it will just fall back to the earth and advance slowly like a normal enemy. However, a ranged enemy that's stunned in shooting range will keep on shooting in spite of it.

• Air: Air pulses apply a stacking 5% damage multiplier to all enemies. Against non-bosses, Air shots apply the same damage multiplier based on the level of Cutting Winds along with knockback. Against bosses, air shots do nothing but air pulses work as normal.

Air's damage boost stacks additively with itself from both sources. For example with 25% cutting winds, an enemy hit by 2 air shots and 2 air pulses would take (25+25+5+5)=60% increased damage from the next shot

• Electricity: Electricity shots apply a fraction of their origin shot's damage to all enemies in a small radius around the target. Electricity aura deals (1/10 of the tower's maximum health) * (number of targets in range) to each target in range.

Electricity shots' splash damage is secondary damage based wholly on the damage dealt to the shot's target: any damage multipliers affecting the target will increase the damage of the splash and no multipliers affecting the enemies in the splash zone will apply. In fact, electric enemies can take damage from the splash without elemental piercing (they just can't release a splash when they're hit with an electric shot). Electric aura's damage is based on the tower's final HP, including percent bonuses from research and health boosts granted by fortify.

(My favorite strat right now is focused on electricity aura and fortify :D )

• Darkness: Reduces the current health of a target by a fraction. Shots remove HP based on the level of the void upgrade and aura pulses always remove 5%.

Darkness and nature calculate damage at the same time, just before damage takes place. That means when both are maxed (void 20% and spirits 10%) every shot that triggers both will remove 30% of the target's current health On Top Of damage from the bullet itself. And both effects work on bosses. And don't forget that the damage applies in full no matter how little health your actual shot damage does to the target. These two are imo vital to any build that can afford them in both shot and aura form

• Nature: Reduces the current health of a target by a fraction and heals the tower for that amount. Nature shots steal health based on the level of the spirits upgrade and nature pulses steal 1% of target current health.

You can maximize shot output for much cheaper than you can boost damage, so it's not too hard to squeeze a flurry of nature/dark shots into a defense focused build's budget. If you want to focus on damage instead, one shot with nature & dark will get you halfway to the crucial execution range before you even consider any bullet damage.

I'm gettin tired now so heres just a few more neat things to know:

• A bouncing bullet can bounce to the same enemy more than once
• Execution will only kick in if a bullet hits an enemy below 40% health, so secondary damage that happens at the same time as the bullet (e.g. nature and darkness shots) which brings the target below 40% will not cause that bullet to trigger execution.
• Getting an upgrade through gambling makes it cost more basic resources as if you'd bought it with basic resources, rather than buying it with blueprint resources
• Purification has a chance to trigger with every bullet that hits an enemy

That's all I have to report for now. If you have any questions or ideas or research of your own that you wanna share, post it in the comments!