Start the duel by using the skill to build a labyrinth to stall the duel, shuffling 2 cards that you don't need early in the duel.
If you have 1 Thunder Dragon, you can use its effect to get 2 and use them for the skill. Keep in mind that if you get another thunder dragon in your draws later, do NOT use its effect to get the other thunder dragon, since it is needed for the fusion.
Choose the ones that don't help you draw, so you can use the spell/trap cards like shard/jar of greed right after you summon labyrinth.
Speed up the process
Once you have your labyrinth set up, keep using any/all the cards that you have that can help with drawing more cards.
Equip wonder wand to gravekeeper's recruiter and activate the wands effect immediately. This will let you draw 2 cards, as well as a gravekeeper monster, which you can use to get another recruiter to your hand.
If you get a thunder dragon, check your graveyard to see if you have 1 in the graveyard. This will let you know if you already activated its ability earlier in the duel or not.
Mooyan Curry is used to heal your opponent, not your own LP. If used before the turn that you deal finishing damage, you will get "Comeback Victory" bonus.
2 Thunder Dragon are needed to fusion summon into Twin-Headed Thunder Dragon for fusion summon bonus, as well as helping Vassal reach 10,000 damage from its attack. If you ended up throwing 2 thunder dragons away, the duel is still salvage-able if you summon Gravekeeper's Recruiter when you have 1 card left in your deck and equip him with Wonder Wand. You will not be able to get 8k Duel Assessment, but Vassal can still reach 10,000 damage.
After using Shield & Sword, you NEED to switch Labyrinth's position into attack before entering battle phase. This is because Union attack will only add up attack position monster's attack.
Against Mai Valentine
This deck can be used against Mai, but you will have to play it differently.
Due to Amazoness Sage's ability, Mai will often use sage and attack into your Labyrinth to destroy your spell/trap cards. This will cause her to inflict battle damage on to herself, losing you the "effect damage only" bonus.
Once you have the labyrinth on the field, DON'T put any spell/trap cards on the field. This is to make Mai not summon her Amazoness Sage, which will attack the labyrinth in order to destroy your spell/trap card. Pass the turn(s) until she has 3 monsters on the field and no Sage on the field.
Mai will sometimes summon amazoness sage if she has no other monsters to summon. If this happens, don't use spell/trap cards that are not going to be used immediately (ie: Shard of Greed). You can still use Wonder Wand's effect immediately by equipping it on to Gravekeeper's Recruiter. Jar of Greed is fine to use as well, but you will have to set activation confirmation to "Toggle Button" in the settings, and select it to be "on" mode so you can activate it immediately instead of after sage attacks the labyrinth.
It CAN'T be 100% ... oc near to that but could never be 100% no way...
If you trade out vassal with piranha and replace sword and shield and something else with paladin of white dragon and white dragon ritual you can get 8k without union attack.
Final turn use white dragon ritual, sacrifice the wall to summon paladin, sacroficr for a blue eyes, fuse twin headed thunder dragon, summon piranha, double gift of martyr. With a glossy and prismatic card you get above 8k
The labyrinth skill also works with Mako Lvl40, for some reasons, when the labyrinth is banished by the gate, Amphibious Bugroth MK-3 won't attack directly. Mako will just pass turns until he tributes it for legendary fishermen