Crosspathing/Tack Shooter

In Bloons TD 6, it is important to choose the best crosspathing for a specific tower in order to receive the best benefits out of that tower type. Towers have special roles to play for each stage of the game. The Tack Shooter in its core is creating area damage within a focused area.

Introduction
Tack Shooters typically have low range but shoot many tacks per shot, and can be upgraded to improve its area damage. It initially attacks slower than a Dart Monkey, but once upgraded with extra attack speed upgrades it is becomes faster than a typical Dart Monkey. The faster attack speed aspect usually compensates its low range in many scenarios, or extra damage over range for higher-tier Path 1 upgrades.

Path 1 increases attack speed of the Tack Shooter and eventually converts its sprays of tacks into area-of-effect damage. Path 2 improves range and eventually pierce of the Tack Shooter, and can improve its distribution of projectiles. Path 3 focuses on increasing the numbers of tacks, thereby improving the density of the tacks. On most higher-tier upgrades, the crosspathing benefits have certain special-case effects due to how much different they are compared to its lower-tier upgrades.

Tier 2 and below

 * 0-0-0: Quite weak on its own. It is best upgraded to make use of its area effect better.
 * 1-0-0: Faster attack speed, which can be handy when purchasing a 1-0-1 Tack at the start of CHIMPS
 * 0-1-0: Gives the Tack more range & pierce, which can be useful in some situations, but generally is niche if only this upgrade is bought. This also might actually cause the tacks to miss more often due to the fact that the tacks thin hitboxes have to take more time to their target if its trying to hit faster bloons.
 * 0-0-1: Increases the amount of tacks to 10 and increases Ring of Fire damage if the player got that upgrade.
 * 2-0-0: A further increase in attack speed
 * 1-1-0: Increases the attack speed and range of the tacks.
 * 1-0-1: A useful starting tower on CHIMPS, since it can be afforded at the start of the game with just enough cash. Compared to 0-0-2, it is overall stronger overall due to its faster attack speed, but it has 10 tacks per shot instead of 12.
 * 0-1-1: Increases the number of tacks shot and range.
 * 0-2-0: Can be used to pop grouped bloons with a Tack Shooter. It is a precursor of the Blade Shooter and is mostly used on Race Events that enable Blade Maelstrom to do Blade Shooter starts.
 * 0-0-2: A useful starting tower on CHIMPS, since it can be afforded at the start of the game with just enough cash. Compared to 1-0-1, it hits faster bloons more reliably but is slower.
 * 2-1-0: A 2-2-0 without the further increase of range and pierce.
 * 2-2-0: A combination of high pierce, high range, high attack speed for a low-tier Tack Shooter, but still statistically low compared to higher Tack Shooter upgrades.
 * 1-2-0: A 2-2-0 without the further increase in attack speed.
 * 0-2-1: A 0-2-2 without the further increase in the number of tacks shot.
 * 1-0-2: A 2-0-2 without the further increase in attack speed.
 * 2-0-2: Further increases the attack speed and the number of tacks. This crosspath is notable due to it being commonly used for both its Tier 5 upgrades (that is, 5-0-2 and a 2-0-5 Tack Shooter)
 * 0-1-2: A 0-2-2 with the further increase to range and pierce.
 * 0-2-2: Utilizes the extra pierce per tack and maximizes the pierce potential into each tack.

Hot Shots

 * 3-0-0: This specific crosspath is normally simply used as cheap lead-popping with a Tack Shooter. Crosspathing should be done to maximize potential of its damage potential.
 * 3-1-0: Gives more range, which allows it to shoot further.
 * 3-2-0: Even more range plus extra pierce, and this is what makes Path 2 crosspath useful here.
 * 3-0-1: See 3-0-2
 * 3-0-2: Provides +4 projectiles per shot for better single-target damage for cheap.

Ring of Fire

 * 4-0-0: Ring of Fire converts the Tack Shooter into an area-of-effect damage zone, exchanging from a spray of tacks. The range upgrades along Path 2 provide range and pierce, while the extra tack upgrades along Path 3 provide more damage per shot instead of extra tacks. Pick the crosspath based on the needs of the defense, whether it be to cover a wider area or to deal better damage within a short area. Note that Ring of Fire gains a substantial amount of pierce already, but Path 2 still packs the greatest value by giving Tack Shooters the range it needs, especially for a Ring of Fire.
 * 4-1-0: More range and pierce to allow it to attack from further and affect a greater number of bloons per shot. Upgrade further to 4-2-0 for the best results.
 * 4-2-0: More range and pierce optimizes the area at which the Ring of Fire can deal damage.
 * 4-0-1: More damage per shot, allowing the Ring of Fire to handle stronger bloons better. Upgrade further to 4-0-2 for even more damage per shot, especially because Even More Tacks costs only $100 on Medium, a very affordable price for a lot more damage.
 * 4-0-2: Much more condensed damage per shot, but keeps the Tack Shooter's low range. It is wise to add support such as a Primary Mentoring to give it a respectable amount of range.

Inferno Ring

 * 5-0-0: Much higher damage, adds a significant bonus MOAB-class damage, faster attack speed, and regularly spews out exploding burning meteors. Basically a mix between grouped popping and single-damage, all purposed mainly for the late-game against weak grouped bloons and strong single-targets alike. Crosspathing Inferno Ring makes a huge difference to the power of its flame rings, for optimal grouped damage. Strangely, crosspathing has no impact on its meteors.
 * 5-1-0: TBA
 * 5-2-0: TBA
 * 5-0-1: TBA
 * 5-0-2: TBA

Blade Shooter

 * 0-3-0: If pure pierce is necessary, 0-3-0 is okay to start off with, especially when utilizing the "Come On Everybody!" MK. Crosspath depending on the needs, but Path 1 is usually better for the attack speed. This also increases the hitbox of the used-to-be tacks into projectiles that will miss faster bloons less
 * 1-3-0: More attack speed is better for utilizing the extra pierce potential. Increase attack speed again for even more pierce potential.
 * 2-3-0: The best optimization for the extra pierce potential.
 * 0-3-1: Slower than the opposite crosspath, but has more blades per shot. It misses out on the attack speed bonuses, so it tends to do less damage overall. It is somewhat cheaper, however.
 * 0-3-2: Slower than the opposite crosspath, but has more blades per shot. Again, it misses out on the attack speed bonuses, so it tends to do less damage overall. It even cheaper than the opposite crosspath, however.

Blade Maelstrom

 * 0-4-0: Recharging the ability as soon as possible is necessary to use its powerful sprays of blades as soon as possible. Crosspathing does not affect ability, and the main attack becomes no stronger with this upgrade.
 * 1-4-0: Usually used as part of a Blade Shooter. Still, utilize the attack speed further.
 * 2-4-0: Usually used as part of an optimal Blade Shooter.
 * 0-4-1: Same principles as 0-3-1, although weighed less due to the fact that neither crosspath does anything for the ability.
 * 0-4-2: Same principles as 0-3-2, although weighed less due to the fact that neither crosspath does anything for the ability.

Super Maelstrom

 * 0-5-0: Recharging the ability as soon as possible is necessary to use its powerful sprays of blades as soon as possible. Crosspathing does not affect ability, but the main attack does gain +1 damage with this upgrade.
 * 1-5-0: Usually used as part of a Blade Shooter. Still, utilize the attack speed further.
 * 2-5-0: Usually used as part of an optimal Blade Shooter.
 * 0-5-1: Same principles as 0-3-1, although weighed less due to the fact that neither crosspath does anything for the ability.
 * 0-5-2: Same principles as 0-3-2, although weighed less due to the fact that neither crosspath does anything for the ability.

Tack Sprayer

 * 0-0-3: Tack Sprayer already gains a sizable attack speed buff on top of more tacks, so sometimes it's not always a bad thing to leave it without a crosspath. Even still, try upgrading along Path 1 for the greater attack speed. Path 2 can be useful if more pierce is needed, but usually only more worth versus normal bloons.
 * 1-0-3: One attack speed upgrade can make a slight difference to the Tack Sprayer's efficiency, allowing it to produce tacks even faster to deal more damage overall. With Primary Mentoring, spamming 1-0-3 saves a good chunk of money.
 * 2-0-3: Generally the better crosspath due to having substantially higher attack speed (over 2x more attack speed). Use Primary Mentoring and Stronger Stimulant to compensate Tack Sprayer's low range and pierce. If using Primary Mentoring for Sprayer spam, upgrade some 1-0-3 to 2-0-3 to make more use of the faster attack speed of the Tack Sprayers.
 * 0-1-3: Not very useful, as the bonus range provided by said upgrade is too small to be noticeable.
 * 0-2-3: Can be useful if needing to reach more bloons or if the bloons are somewhat dense, as is the case for some early-game rounds.

Overdrive

 * 0-0-4: There is almost no point leaving this upgrade without crosspaths. Pick either Path 1 or Path 2 depending on the needs of the Overdrive, but Path 1 is generally better due to making more use of the "death zone" at the center of the Tack Shooter.
 * 1-0-4: See 2-0-4
 * 2-0-4: Generally the better crosspath due to having substantially higher attack speed (over 2x more attack speed). Use Primary Mentoring and Stronger Stimulant to compensate Overdrive's low range and pierce.
 * 0-1-4: It is wasteful unless 0-2-4 is bought, as it gains a very tiny range boost and literally nothing else.
 * 0-2-4: Can be useful if needing to reach more bloons or if bloons are very densely packed. However, it attacks much slower than 2-0-4 and isn't as good at single-target bloons.

The Tack Zone

 * 0-0-5: There is almost no point leaving this upgrade without crosspaths. Pick either Path 1 or Path 2 depending on the needs of The Tack Zone, but Path 1 is almost always better due to making more use of the "death zone" at the center of the Tack Shooter.
 * 1-0-5: See 2-0-5
 * 2-0-5: Generally the better crosspath due to having substantially higher attack speed (over 2x more attack speed). Use Primary Mentoring and Stronger Stimulant to compensate The Tack Zone's low range and pierce.
 * 0-1-5: It is wasteful unless 0-2-5 is bought, as it gains a very tiny range boost and literally nothing else.
 * 0-2-5: Can be useful if needing to reach more bloons or if bloons are very densely packed. However, it attacks much slower than 2-0-5 and isn't as good at single-target bloons.

Strategy
All of Tack Shooters Tier 5 upgrades fill very different roles. For the Inferno Ring, it does extremely well against grouped bloons and does really well against Moab class bloons. For Super Maelstrom, it excels at high pierce, which makes it extremely well for mid-game for rounds 76 and 78, with its relatively lower price point compared to other Tier upgrades. For Tack Zone it does exceptionally well against Moab class bloons for its price, being possible to afford it comfortably by Round 60.

For Tack Shooter, there are some special crosspath interactions for Inferno Ring that was made so that its lower path could be utilized since before there wasn't any point in increasing the number of tacks it shot because Inferno Ring's effect was in a full 360 degree area. Bottom path increases the damage done to top path. The name applies to Ring of Fire as well.

Outside of Special crosspath interactions, the game asks the player whether they want to counter Tack Zones specific weakness with range with middle path and a path that both increases DPS in different ways, or a full increase in DPS (a X-0-X tack shooter). What's unique about Tack Shooter, is that all Tier 5 upgrades could at least reasonably benefit from all of the other paths, just some upgrades are better at doing so then others.