These combinations have been tested and will all work.

• Double Blue Eyes Summon Combo

Summon Lord of D. and use the Flute of Summoning Dragon to summon two Blue Eyes White Dragons onto the field at once as a Special Summon. Not only that you have two Blue Eyes White Dragons on the field but they have the magical protection from being targeted by magic and trap cards from Lord of D.

• Swamp + Lava Battleguard Combo

This combo is very effective and can inflict tremendous amount damage. It can work in many ways but here are two that will inflict the most damage: 1. Have one Swamp Battleguard in play and three Lava Battleguards in play as well. Your Swamp Battleguard's ATK will be 3300 as long as you have three Lava Battleguards in play! (S. Battleguard's Effect = 1800 ATK + 500x each L. Battleguard you have in play) 2. Have one Lava Battleguard on the field and three Swamp Battleguard on the field as well. Your Lava Battleguard's ATK is now 3050 as long as you have the three Swamp Battleguards on the field. (L. Battleguard's Effect = 1550 ATK + 500x each S. Battleguard you have in play) The problem with this is that you have to have one of them and three of the other, in which I think is quite uncommon to have them all out at the same time. 

• Gain 500 Lifepoints Continuously Combo

Place down an Ultimate Offering card and wait one turn. Play the Dark Hole to destroy all monsters on the field. Then, play the Mysterious Puppeteer and now activate Ultimate Offering for an extra summon. You have to pay 500 lifepoints for Ultimate Offering but you will gain 500 lifepoints back when you summon a monster onto the field due to the effect of the Mysterious Puppeteer. You don't need Ultimate Offering anymore at this point. You should remove it with a Remove Trap so your opponent won't be able to take advantage of it as well. Every turn, summon more monsters to gain 500 extra lifepoints as long as Mysterious Puppeteer is in play. 

• Complete Destruction Combo

Play this combo only when your opponent has quite a few strong monsters in play; like ATK power over 1000. Place a Trap Hole face-down. Play the Change of Heart to get control of one of your opponent's strong monsters. Play Raigeki to destroy the rest of your opponent's monsters. Play Monster Reborn the reborn the best monster out of all the monsters you destroyed. Attack your opponent's lifepoints. When your opponent gets back control of the monster you took control of, play the Trap Hole and BOOM! Bye-bye puny monster!