Amp Spire

Overview

 * This tower increases the damage of other towers within its range by a percent amount.
 * If a tower is within the range of multiple AMP Spires, the tower will only be affected by the AMP Spire that grants the highest increase.
 * Unlocked at Rank 12.
 * The area of effect of the Amp Spire increases when upgraded to rank 3, similarly to the Range spire. For ranks 1 and 2, this area is a 3x3 square around the spire. For level 3 Amp and Range Spires, the area of effect is a 5x5 square without the corner blocks (another way of stating this is "two straight blocks away, or one diagonal and one straight block away, but not two diagonal blocks away")
 * Its range can be increased by the Range Spire.
 * Overcharging this tower increases the damage increase effect by 1 percentage per 50 resources invested (=2% per 100 resources = 0,02%/resource)

Notes & tactics

 * This tower is a great addition to the maze later on in the game and is one of the best extra towers to have in Survival mode, where it can help to keep the damage towers capable for long vs the increasing health of the lumes.
 * Some comparisons with other support towers
 * The Range spire is a tower, generally more capable and often wanted even in just early-to-mid game in order to buff towers to a certain degree like covering a certain area or being able to grab a boss in sight, or just as a good support. Still the Amp is usually not too much behind and can be safely put as a support. Whether to pick an Amp or Range spire at a certain part of the game is dependent on some factors, but when it comes to an overall comparison or preference, usually the Range spire is wanted to come earlier. Some towers like ACP, Focus, Anti-air & Drone tend to benefit more from the Range spire, while other like Violators, Rockets, Orbital strike relays & Anti-air usually don't benefit too much from it and an Amp can be safely picked instead of the Range spire or at an earlier stage, especially if the map is small or has small clusters of areas.
 * The Slow fields, Kairos & Mind control spire have the plus of being helpful not only for the towers as they improve their damage by allowing them to fire/hit more times against the lumes, but also being helpful for the weapon damage, as the slowed/controlled enemies are easier targets, including such for weakspots. However, whether to hurry for an Amp or for another support tower of these three mentioned ones is dependent on some factors like enemy armor, type of enemy attacks, damage towers and so on. If enemies have lots of armour, picking Amp before a slowing tower is a fine way to go. If the used towers have very high range (e.g. Violators, Rockets, Anti-air), they actually don't benefit very much from the slowing effects that would cover just a little part of their range and an Amp would usually either have the same effect or 'd be more appropriate. The Mind control spire can help greatly lategame as well, but against the ground bosses it has some side effects, leading to parts of the maze being destroyed or towers to get stunned, which technically exclude it fully or partially for such maps.
 * The Makeshift cannons as semi-support towers usually come after all the possible regular support towers have already been put in action, since they are also somewhat dependent on most of them, although not very dependent on the Amp, and need high abundant resources to improve their numbers and their range to ensure more frequent stunning of enemies, while also careful positioning in order to not block the sight or the fire of some projectile-using towers. The Makeshift cannons benefit well from slowing & stopping effects.
 * While the simple generall "rule" is that sometime after some more damage towers have been placed and presumably a bit overcharged, an Amp would do some good job around, actually all damage towers in the game at a certain moment of overcharging are either granted the same amount of damage that a certain level Amp/Amp overcharge would grant them, or would even benefit more by a simple Amp than rushing for overcharging. This, however, is more complicated for the Focus tower, since it benefits more of overcharging than from any additive buffs, thus showing weak synergy with the Amp tower. In the notes of all damage towers such calculations have been done for the specific overcharge values (thresholds) and correlations with the random levels and overcharges of the Amp.

=Optimal Usage Calculations=

Introduction
Distributing resources between your Damage Towers and the AMP Spire is always a balancing act. Due to the nature of how the tower's DPS synergizes with the AMP's percent damage increase there is no one fixed distribution of total resources between Damage Towers and the AMP Spire (i.e. always 80% to Damage Towers and 20% to the AMP Spire). In fact the optimal distribution keeps shifting the more resources are available for allocation. It is of note that the average DPS per resource of the built towers has no effect on the optimal distribution.

The following is a detailed discussion of the underlying calculation method. If you only wish to quickly calculate the optimal distribution, you can skip to the Reference Table further below.

In-depth Explanation
The following piecewise-defined function describes the relationship between the amount x invested into the AMP Spire of the total resources c and its effect on total DPS dealt by the towers (including the AMP Spire's bonus):



x: Amount of resources allocated to the AMP Spire

c: Total amount of resources available for allocation between Damage Towers and the AMP Spire

a: Average weighted base DPS per Resource of all Damage Towers impacted by the AMP Spire's bonus

Note that the parameter c only comprises the total amount of resources available for allocation between the AMP Spire and Damage Towers impacted by the Spire's range. Resources that go towards non-damaging towers (i.e. Slow field Dispenser or Range Spire) or damaging towers not in range of the AMP Spire are not counted towards the parameter c.

The following shows an exemplary curve plotted using the afformentioned function:



In this example a is set to 1 and c is set to 6000. The red lines indicate the position of x at which the function's value is maximized. In other words, in the case of c=6000 a budget of 500 resources must be allocated towards the AMP Spire and the rest of 5500 resources must be spent on Damage Towers in order to maximize the total DPS. Note that an increase or decrease of parameter a will only affect the total DPS, but has no impact whatsoever on the optimal distribution of resources. This means in the case of c=6000 the optimal distribution will always remain 1:11 (500/5500).

Reference Table
''Parameter c: The amount of resources that will be distributed between Damage Towers and the AMP Spire. This only applies to Damage Towers within range of the AMP Spire and does not include non-damaging towers such as the Range Spire or the Slow field Dispenser.''

''Parameter x: Indicates the portion of c that needs to be invested into the AMP Spire for optimal DPS. Naturally, the remainder (c-x) must be invested into the Damage Towers.''

Due to the dynamic relationship between parameters x and c together with the complexity of the function itself, calculating the optimal resource distribution on-the-fly becomes quite unwieldy. For convenience's sake, a reference table has been calculated using appropriate software. Simply choose the value for parameter c that approximately matches your current budget and you can read the optimal value for x.

1for values of c that exceed 1'000'000 --> x= c/2