These are your typical leader Heroes. Each of them comes with a Command Ability and each is a wizard. Though none of them can use summoning magic as such, each Abhorrant variant can summon new units. Ghouls for the footslogger, Crypt Horrors/Flayers for the one on Terrorgheist, Courtiers for the one on Zombie Dragon and any of your choice for the Archregent. Thanks to the non-existence of summoning magic in this army, these Commands are the only way to set up entirely new units. Compare Commands and unique spells to find out which ones you want to have in your army.
*'''[https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/AoS_Flesh-eater_Courts_Warscroll_card_Abhorrent_Ghoul_King_on_Royal_Terrorgheist.pdf Abhorrant Ghoul King on Terrorgheist]:''' This count also as '''Behemoth'''. Oh heck yes. The Ghoul King adds a lot to the already powerful Terrorgheist, such as magic and a Command Ability. This guy can grant a 5+ save-after-the-save to a Flesh-Eater unit and can summon new units of Crypt Flayers or Crypt Horrors. Other than that, it's a Wizard, it has a Command and it has three powerful melee profiles in addition to a dangerous not-a-breath-attack. Remember, his command ability has some serious utility. Flayers have a ranged attack, which while bad at long range, will do some damage. Horrors are not bad, and can divert your opponent's attention and effort from your mainline, even worse if they get a charge off.
*'''[https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/AoS_Flesh-eater_Courts_Warscroll_card_Abhorrent_Ghoul_King_on_Royal_Zombie_Dragon.pdf Abhorrant Ghoul King on Zombie Dragon]:''' This count also as '''Behemoth'''. Exactly what it says on the tin. Just like the variety on the Terrorgheist, this one here has some seriously powerful buffs. First of all, as a Command, he can summon new Courtiers OF ANY TYPE (who can then proceed to summon more foot soldiers). Then, his unique spell makes a 10" bubble centered on the Ghoul King which grants rerolls To Wound to ALL Flesh-Eater models. On top of that, the Zombie Dragon heals D3 Wounds each Hero Phase. Both mounted Ghoul Kings are excellent choices, but eat points REALLY fast. This King's command ability is excellent. To put it simply; ALWAYS summon a Varghulf Courtier. He's a high damage fighter, who replenishes ALL your guys, is fast, and still gets a Look Out Sir! This summon should be used wisely, and can be used for multiple ways. Maybe an ambushing unit of ghouls needs a hero's Forward To Victory, or a Blisterskin Flayers unit wants a Feeding Frenzy buff but are too far. This can go a long way.
*'''Abhorrant Ghoul King:''' Not that murderous when compared to a Vampire Lord in terms of killing power, but absolutely amazing when compared to the average Wizard. Their unique spell grants a Flesh-eater unit one more attack with each melee weapon, which makes Crypt Ghouls and Horrors better and Varghulfs terrifying, but if you cast this on a Ghoul King on Terrorgheist, he'll pluck whole units apart by himself. Another thing that needs to be addressed is that a Ghoul King is a fucking cockroach. 6 Wounds at a 4+ save and a regeneration of D3 Wounds a turn means the enemy either dedicates entire war machine salvos to kill this guy or he'll be good as new two turns later. Sure he can't go toe-to-toe with an Ironjaws Megaboss (who can?), but he'll survive stuff that could easily overkill most other buffers and wizards. His command ability seems weak, but can be very strong in Morgaunt. 10 Ghoul units get an extra attack if close enough to a Courtier, significantly increasing their damage output. Furthermore, these units can claim objectives and just be incredibly annoying. Plus it's free if used closeby the Charnel Throne.
*'''Abhorrant Archregent:''' Essentially a souped-up footslogger Ghoul King. Has an extra wound and attacks, but his major advantage over the vanilla one is his magic, with the ability to cast an extra spell and a variant of the Ghoul King's spell that grants d3 attacks. Also heals a flat three wounds per turn. He also combines the summoning abilities of all the different Abhorrent Ghoul Kings. He can either summon a unit of 20 Ghouls, 3 KNIGHTS or a Courtier. This adds a degree of flexibility mid-game. If you take one, place him close to the (free) charnel throne to use his summon ability without paying a CP. Remember, he is NOT a dedicated fighting hero, but he can do some work. Try not to risk him in melee. His support value is just too good. He's basically a direct upgrade over a foot Ghoul King. And don't forget, he can regenerate 3 wounds. The Ghoul King's a cockroach? Fuck that noise. This guy will never die unless your opponent truly commits to murdering him off the board. Remember, his command ability is crazy versatile. Use it wisely, according to the situation at hand.
*Also, remember that as his spell and the normal foot Ghoul King's are different, they stack. A potential 4 extra attacks on a unit is ruinous, especially with feeding frenzy.