| OH GOD, NO!|
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There are three main types of clowns you encounter, but they can all be identified by their red hair and colorful make-up: a white face with large black eyebrows, blue lips, and red eyes apparently leaking blood. You can find clown make-up of your own in locker #37, which gives the wearer the ability to explode on death like an enemy clown (specifically, the Psycho variant).
The first type of clown you'll meet wears a fancy suit and carries a Hand Axe. It is classified as a Close-Quarters Battle unit, allowing it to use its axe for 1 AP per swing, and its suit gives 9 Max AP and +6 AP Gain. It is also fairly durable (32 HP), but it lacks any AC, so it's not too hard to kill.
However, the Saucy Clown's greatest asset is the destructive explosion it creates upon death, dealing 32 damage to everything up to two spaces away from itself (essentially, a 3x3 box with one extra space at the top, bottom and sides). This is enough to kill all but the hardiest characters, and the Saucy Clown's proficiency for melee combat often puts it in the perfect position to hit your team with its blast.
By the time you encounter clowns, you should have the JHP Ammo or the Hook/Sanford's Head combo available, so your best option for dealing with Saucy Clowns is to keep them stunned until you can get your characters out of its blast radius (vertical movement is extremely useful here). Since their explosions can hurt their allies too, consider positioning enemies in a way that will catch them in the clown's death explosion.
The second clown variant wears "Tattered Rags" or "Bloody Tatters" and has zombie claws for combat. Despite looking more or less like a zombie, it is far less dangerous in battle - it has only 16 HP, no AC or AP bonuses, only deals 3 points of damage with each claw attack (although it does halve AC), and lacks the "Bloodlust" ability that provides most of a zombie's threat.
Its death explosion has the same range as the Psycho Clown's version, but only deals half the damage. Unfortunately, 16 HP is still enough to kill or severely wound most of your standard character builds, and any other enemies caught in the blast will be transformed into zombies instead of dying outright. Zombified enemies lose their weapons and headgear in favor of claws and a zombie head, respectively, but they retain their body armor and have their current HP doubled (a bonus that stacks if the same enemy is caught in multiple Zombie Clown explosions).
The Zombie Clown's explosion can be evaded in the same way as the Psycho Clown's - but be careful with your stun attacks, as it has only half of the first version's HP. On the other hand, you'll want to do the exact opposite in relation to nearby enemies - kill or otherwise separate them from the Zombie Clown before they can become twice as hard to kill (literally).
If many Zombie Clowns are present in a room, you may want to consider whittling down other foes as much as possible while leaving enough AP to kill one of the undead clowns - the resulting chain reaction will give any survivors massive HP boosts, but even multiple doublings won't mean much if the recipient has only single-digit HP remaining. Alternately, you can simply let the Zombie Clowns detonate and then stun-lock the remaining super-zombies while you wear them down the old-fashioned way.
The final type of clown you'll find wears a "White Tuxedo" and carries a Desert Eagle. This variant is a bit of a show-off; any Disco Clowns in a room will bust a move under a spotlight before the battle begins.
Unlike Psycho and Zombie Clowns, Disco Clowns have an AC of 1, allowing them to block a few blows and compensate for their somewhat low HP of 16. Their pistols deal 4 points of damage within a 4 square range with each shot, and their CQB class as well as +5 AP Gain allows them to fire frequently every turn. Their final explosion has traded damage for range; it does no damage whatsoever, but hits your characters no matter where they are in the room and has a high chance of stunning them (similar to a Flashbang grenade). The stunning effect does nothing to the Disco Clown's allies.
Since you can't outpace their explosions, you should focus on mitigating the potential stun effects of the Disco Clown's last laugh; keep track of the clown's HP (the "TAC Mask" is useful for this) and make sure you've healed up your team and positioned them where you wanted before finishing it off. Try to eliminate any supporting enemies and save the Disco Clown for last - its stunning explosion is much less useful when there's no one to take advantage of it. If anyone survives without being stunned, consider dropping a Smoke Grenade or a Flashbang of your own to leave the enemies hindered until your team can recover.