If you're playing the OCG, you may know this better as a Chess deck. Virtually all of the archfiend monsters are chess-themed (King, Queen, Bishop, Knight, Rook, Pawn) so many people simply choose to call this a Chess deck.
All of the 4* Archfiends (except Soldier) have a cool negation effect. Whenever an Archfiend monster is targeted by an opponent's magic, trap, or monster effect, you can roll a die and if the result is a certain number then you can negate the card. Free negation if you roll the right number...not bad at all.
I'm a huge fan of Darkbishop Archfiend, but I know many people aren't. If Darkbishop is on your side of the field and an Archfiend is targeted, you can roll the die for the specific monster, but then you can also roll the die for Bishop to negate it (and Bishop has a 50/50 chance of negation). King and Queen negate cards if the roll is 2 or 5; Bishop negates if the roll is 1, 3, or 6. If something targets the King or Queen while Bishop is on the field, there's a 1/6 chance that the effect will succeed. That's VERY nice.
Just as a side note, let's take a look at cards that target monsters, so you can get an idea of what Archfiends can negate. Exiled Force; Zaborg the Thunder Monarch; Chaos Sorceror; Goldd, Wu-Lord of Dark World; Old Vindictive Magician; Newdoria; Tsukuyomi; Snatch Steal; Brain Control; Book of Moon; Enemy Controller; Sakuretsu Armor; Bottomless Trap Hole; the list goes on and on. You WILL encounter those cards during a tournament. Archfiends have decent chances at negating them whenever they're used, so their effects can easily turn the tide of the game. Simply negating one Zaborg can completely throw off your opponent's strategy, forcing your opponent to go on the defensive FAST.
In addition to the negation effects, the effects of the specific Archfiends are pretty sweet as well. Shadowknight isn't in this deck, as it's generally useless. It's just a generic beatstick; 2000 attack, but the damage it does it halved. Desrook allows you to discard itself to special summon a Terrorking from the graveyard immediately after one is destroyed. Vilepawn has a Marauding Captain effect; no other Archfiends can be attacked if you have one on the field. Infernalqueen increases the attack of one Archfiend on the field for a turn, on both yours and your opponent's turn. Terrorking cannot be normal summoned if there's no other Archfiend on the field, but it has 2000 attack and a built in Hades effect. Terrorking will be your main monster in this deck. Soldier has no effect, but it's still an Archfiend and is a 1900 monster, so it's very stable...which is something this deck may need at times. Archfiend of Gilfer is one of the most interesting Archfiends in the game - when it is sent to the graveyard, you can equip it to a monster on the field to lower its attack by 500. With 2200 attack, it can stand up to Cyber Dragon, and with 2500 defense it can survive Jinzo or a Monarch. However, it can miss the timing very easily, so be sure that you know EXACTLY when to use its effect in a major tournament.
There's surprisingly a lot of support for Archfiends; moreso than other themes revolving around field cards. Checkmate allows you to sacrifice an Archfiend to allow a Terrorking to attack directly. I'm not a huge fan of it, but you could use it. Falling Down is another support card. Think of it as a Snatch Steal, but you take 800 points of direct damage a turn as upkeep. This does NOT get negated by Pandemonium. Archfiend's Roar is actually pretty nifty. Pay 500 LP to special summon an Archfiend from your graveyard, but it's destroyed at the end of the turn and cannot be offered for a tribute.
The downside to most of these monsters is that they have a LP cost each turn. This LP cost is NOT optional, but Pandemonium gets rid of it. I prefer Pandemonium to Battle-Scarred since Pandemonium negates ALL costs rather than making the opponent pay the same cost for one monster. Pandemonium can also be searched out with Terraforming, and whenever a monster is destroyed you can search for another Archfiend, making each Archfiend like a Mystic Tomato or Apprentice Magician.
Archfiends are one of the most overlooked types in the game. Being Fiend, they're often overshadowed by Necrofear and Dark World...but they can cause a lot of disruption when used correctly. Play around with them and see what you can come up with.
Monsters - 19 (3 Tribute, 16 Non-Sacrifice)
Magic/Spells - 13
Traps - 8
