If you use "One for One", discard a "Wight" monster to power this up.
To take this strategy up a couple of notches, discard "Wightprince" to use it's effect to dump "Skull Servant" and "The Lady in Wight" into the graveyard. This will allow "King of the Skull Servants" to be summoned with at least an ATK of 3000 with very little effort.
You can discard a "Skull Servant" to activate "Mask Change II", and use it on another "Skull Servant" or a "Wight" monster to send it to the Graveyard and summon "Masked HERO Dark Law", which will also result in your opponent's Graveyard being sealed off, while this card's ATK will increase by 2000.
"Koa'ki Meiru Gravirose" send level 3 and lower monsters from your Deck to the Graveyard. All the "Wights" count for this. Have a second in your Hand to prevent its Self-destruction effect.
"Exodius the Ultimate Forbidden Lord" can be used in conjunction with "Skull Servant" Decks. "Exodius" can send "Skull Servants" to the Graveyard, powering itself up at the same time it powers up "King of the Skull Servants".
You can use "Chain Destruction" when summoning a "Skull Servant", "The Lady in Wight" or "Wightmare" to throw two copies of the selected card into the Graveyard (from your Hand and/or Deck) and power up "King of the Skull Servants".
This can also be used on "King of the Skull Servants" if the amount of "Wight" cards are 2 or less at activation.
When you have 3 "Skull Servant", 3 "The Lady in Wight", 3 "Wightmare", 3 "Wightprincess, and 3 "Wightprince" in the Graveyard, it is better to have 3 "King of the Skull Servants" with 15000 ATK each than to have 2 Kings in the graveyard and 1 on the field with 17000.
In fact, if you remove 2 "King of the Skull Servants" from your grave for the effect of two "Phantoms of Chaos", and summon those kings with "Return from the Different Dimension", you can have five "Kings of the Skull Servants'" on the field with a grand total of 60000 ATK (but "Phantom of Chaos" cannot damage the enemy).
Another possibility is to play "Morphtronic Magnen Bar" while you have two attack position "King of the Skull Servants" giving it up to 26100 ATK, Equip "Morphtronic Magnen Bar" with "Opti-Camouflage Armor" and you can OTK just about anyone.
You can use "Creature Swap" to switch control of this card to you opponent, and it will have 0 ATK. Then, when you destroy the "King" in battle, you can bring it back to your side of the field with it's effect.
Cards like "Necroface" and "Shutendoji" can help preserve the monsters you banish to revive the "King", but both cards are equally capable of banishing monsters themselves.
"Doomsday Horror" is a good side card to have at hand, in case your opponent has a card such as "Soul Release". Or you can use its effect to return to your Graveyard copies that you banished for this card's effect.
This card can give a great ATK boost to "Junk Warrior", depending on the number of "Skull Servants", "The Lady in Wight", "Wightmare", and copies of this card in your Graveyard.
If you Summon this card while there are 3 "Skull Servants", 3 "Lady in Wights", 3 "Wightmares", 3 "Wightprinces" and 2 "Kings of the Skull Servants" in your Graveyard and "Archfiend Zombie-Skull" on your side of the field, you will have a monster with 14000 ATK that is immune to Spells and Traps; almost indestructible.
It's good to know that you can use "Inferno Reckless Summon" when you Special Summon "Skull Servant" to get 3 out for the Synchro Summon of "Archfiend Zombie-Skull" to get them quickly into the Graveyard for "King"'s ATK boost.
You can use this card in a Lightsworn deck, to easily send up to 12 of the "Wights" and return at least one with "Mezuki" and combine with "Judgment Dragon" to make a easy OTK.
You can use "Morphing Jar" to quickly deposit "Skull Servants" into your Graveyard. This can also help with hand advantage, as you will be likely discarding many of the "Wights" to the graveyard.
Your opponent can quickly OTK you with a "Magic Cylinder" if you choose to attack with a "King of the Skull Servants" with an ATK of 8000 or more. It's usually wise to have either "Barrel Behind the Door" or "Ring of Defense" set before attacking with "King of the Skull Servants".
Its possible to get an OTK by using the Xyz Monster "Baby Tiragon" while only using Level 1 monsters.
"PSY-Framelord Omega" can return the monster banished by this card's effect back to the Graveyard.
Use the effect of "Painful Choice" to make your opponent to discard 4 "Wights" to power up "King of the Skull Servants". Activate "Monster Reborn" to Special Summon a "King of the Skull Servants" that was sent to the Graveyard through this effect. It is wise to choose between the Effect "Wights" because your opponent gets to choose which card you keep, and they will likely choose a "Skull Servant" if you allow them to.
This card is a good candidate for "Last Turn", since it gains 1000 ATK for every "Skull Servant" and copy of itself in your Graveyard. Even if they manage to destroy it by battle, you can banish a "Skull Servant" from your Graveyard to revive this card, resulting in a draw during the End Phase.
Ironically, this card can counter "Last Turn" for the same reasons.