Necromancer: Unpopped Army

"Reanimate recently popped enemies as servants to destroy the Bloons."

- In-game description

 (also known as Necromancer or Necro) is the fourth upgrade of Path 3 for the Wizard Monkey in Bloons TD 6. It causes all bloons popped near the Wizard to become undead bloons that travel towards the entrance and deal damage to bloons they touch (including Purple and Lead Bloons). Each undead bloon deals 2 damage per hit and has a random amount of pierce between 2 and 11, lasting for up to 10 seconds. Level 11+ Ezili increases the pierce of undead bloons by +50%, which is applied before other buffs to pierce. Adding Guided Magic improves lifespan of all summoned undead bloons by +42%, from 175 units to 250.

The undead bloons are stored in a personal graveyard, local to each Necromancer, and a given Necromancer can store up to 500 accumulated bloons popped for up to 2 rounds. Undead bloons spawn +10% faster for every 100 graveyard units, up to +50% faster with a graveyard of 500. Additionally, all the Wizard's attacks deal +1 damage per 200 graveyard units in the personal graveyard.

It costs $2,380 on Easy, $2,800 on Medium, $3,025 on Hard and $3,360 on Impoppable.

Appearance
Unlike the appearance of the Shimmer predecessor, the Necromancer's cloak is almost entirely black, with purple trims on the sleeves and the hood. The hood now is adorned with a skull that has glowing green eyes, and the Necromancer's skin has also become entirely green (although most of his face is hidden by mummy bandages). The Necromancer also wields a skull-topped staff, which seems to be telekinetically controlled.

Graveyard Units

 * See also: Undead Bloon

Accumulation
The Necromancer receives graveyard units when bloons are popped within 70 range of the Necromancer (these do not have to be popped by the Necromancer himself). Each layer popped gives 1 graveyard unit; for instance, popping a MOAB only gives +1 graveyard unit, but popping an entire Rainbow Bloon gives +46 graveyard units. However, from Rounds 81+ when Super Ceramics arrive, popping a Super Ceramic layer gives between 7-13 graveyard units, inclusive, to compensate for the fewer child bloons per Super Ceramic. Each Necromancer's graveyard can only hold up to 500 units.

Depletion
Every time a Necromancer summons undead bloons, it will randomly consume 1-10 graveyard units. 1 to 4 undead bloons are summoned at a time, each consuming the previously mentioned quantities of graveyard space. Each undead bloon has 1 base pierce and gets bonus pierce equivalent to how many graveyard units were consumed.

For every 100 units in a Necromancer's graveyard, he summons undead bloons +10% faster, up to 50% faster at the max 500 graveyard units. Each undead bloon also gets 1 bonus damage for every 200 graveyard units (up to +2 at 400-500 graveyard units) that the Necromancer had right before he summoned the bloon.

Graveyard units stored in a Necromancer last for up to 2 rounds before being automatically depleted.

Tower Prices

 * x-x-4 Price on Easy: $2,380 (Total: $4,800)
 * x-x-4 Price on Medium: $2,800 (Total: $5,675)
 * x-x-4 Price on Hard: $3,025 (Total: $6,105)
 * x-x-4 Price on Impoppable: $3,360 (Total: $6,780)

Summary
Necromancer: Unpopped Army is one of the strongest towers for its cost as of Version 21.0. It can deal serious damage if it is can amass undead bloons, but it is less effective against waves of MOAB-Class Bloons, since each one generates very few undead bloons when popped. It is one of the best towers in the earlier mid-game as a cleanup option. Pairing it with nearby towers for extra damage helps optimize the Necromancer's overall performance and keep its graveyard full more often. If placed in a good position with supporting damage, one Necromancer can easily reach well over 100,000 pops by round 100.

Tips

 * Always provide another offensive tower nearby, whether it is another Necromancer or any other suitable tower. This reduces leaks while the Necromancer is summoning undead bloons and contributes to the Necromancer's graveyard.
 * This is especially useful on rounds where there are not many low-tier bloons for the Necromancer to begin summoning and snowballing from.
 * Position the Necromancer on areas of the track where you want the bloons to spawn by placing only that track within its range.
 * When placed near the start of the track lane, Necromancers can be used as effective anti-stall on single-lane maps. For even better performance, add even more Necromancers, a Prince of Darkness, add Alchemist buffs, plus other towers that deal effective MOAB-class damage (e.g. MOAB Maulers).
 * Unlike ability-based towers, Necromancers benefit the most from anti-stalling. This is because anti-stalling a round will minimize the depletion of the graveyard and therefore store more undead bloons for later rounds.
 * Since all the Necromancer's attacks deal bonus damage with a fuller graveyard, it is usually better off going for 0-2-4 rather than 2-0-4 to boost Wall of Fire. Additionally, greater damage within the Necromancer's direct range means the graveyard can be filled faster.
 * Undead bloon spawning always ignores line of sight, even if the Necromancer itself can't see over the walls. Undead bloons only require an overlapping track space to spawn from.
 * Necromancers should be placed where the majority of your towers will attack, in order to gain as many undead bloons as possible from the nearby popped bloons.

Trivia

 * This upgrade and the Prince of Darkness are the only upgrades that spawn undead bloons.
 * Undead bloons are slightly off-center on tracks, similar to Bloons in early games of the BTD franchise.
 * Undead bloons aren't affected by the Big Bloon Option. This also occurs with the undead MOABs and BFBs spawned by Prince of Darkness.
 * A single bloon popped will count towards the graveyards of all applicable Necromancers nearby, so multiple Necromancers can spawn additional undead bloons even if only a few Bloons are popped (ex. 3 Necromancers will summon 3 undead bloons for 1 Red Bloon).
 * In Version 23.0, although Prince of Darkness's damage stack requirements have been nerfed to per 300 graveyard space instead of 200, this had no effect on the normal Necromancer. This means that the normal Necromancer can still deal 4 damage at maximum capacity. When tested out, a Rainbow Bloon still turns into Yellow Bloons, implying 4 damage has been done by the undead bloons.
 * Necromancer: Unpopped Army is the second tower to create a Bloon type. The first one being the Ice Monkey creating Frozen Bloons.