This page will explain both Mannawydan Fab Llyr Bosses!
As you should know this duel is placed in stonehenge so it has a certain setup with a custom type for the battlefield.
Here they are:
Chakra(1891):
F M M M M M F
M M L D L M M
M L D D D L M
M D D D D D M
M L D D D L M
M M L D L M M
F M M M M M F
Skull Knight(1985):
F M M M M M F
M M L C L M M
M L C C C L M
M C C C C C M
M L C C C L M
M M L C L M M
F M M M M M F
C=Crush
L=Labyrinth
F=Forest
M=Meadow
D=Dark
The only tip i can give you is, for the 1985 one, you can use greenkappa to take him out in one shot.
(Get it? Greenkappa? Lol it Caps the highest monsters attack and defense!)
The decks are as follows:
Chakra(1891):
1- Barrel Dragon 2- Berfomet 3- Berfomet 4- Berfomet 5- Bickuribox 6- Blue Eyes White Dragon 7- Crimson Sunbird 8- Dark Hole 9- Dark Magician 10- Gaia the Fierce Knight 11- Gate Deeg 12- Gate Deeg 13- Gate Deeg 14- Kaiser Dragon 15- Kazejin 16- Kinetic Soldier 17- Labyrinth Tank 18- Magic Drain 19- Magic Drain 20- Magic Drain 21- Megamorph 22- Metalmorph 23- Meteor Dragon 24- Meteor Dragon 25- Red-Eyes B.Dragon 26- Red-Eyes B.Dragon 27- Red-Eyes B.Dragon 28- Riryoku 29- Riryoku 30- Riryoku 31- Royal Decree 32- Sanga of the Thunder 33- Seiyaryu 34- Skull Knight 35- Suijin 36- Summoned Skull 37- Summoned Skull 38- Thousand Dragon 39- Toon Summoned Skull 40- Zoa
Skull knight(1985):
1- Cosmo Queen's Prayer 2- Crush Card 3- Curse of Dragon 4- Curse of the Tri-Horned Dragon 5- Dian Keto the Cure Master 6- Dian Keto the Cure Master 7- Dark Elf 8- Dark Elf 9- Dark Piercing Light 10- Feral Imp 11- Gemini Elf 12- Gorgon's Eye 13- Grave Robber 14- Gravity Bind 15- Gravity Bind 16- Just Desserts 17- Just Desserts 18- Koumori Dragon 19- Kuriboh 20- Last Day of Witch 21- Megamorph 22- Mirror Force 23- Mirror Force 24- Multiply 25- Paralyzing Potion 26- Princess Tsurugi 27- Queen of Autumn Leaves 28- Raigeki 29- Raigeki 30- Riryoku 31- Riryoku 32- Riryoku 33- Skull Knight 34- Skull Knight 35- Solomon's Lawbook 36- Time Seal 37- Tremendous Fire 38- Tremendous Fire 39- Warrior Elimination 40- Wide Spread Ruin