Note that unlike many other monsters such as "Catapult Turtle" and "Dark Strike Fighter", the effect of "Cannon Soldier" can be used multiple times per turn, allowing for potentially very heavy damage if several monsters are Tributed at once or Tributed and repeatedly. A list of potential OTKs follows, all involving combos that lead to continually reviving monsters and Tributing them:
Loop: Tribute "Ragigura" for this card's effect, then Special Summon it via the effect of "Faultroll". If a "Faultroll" is in your Graveyard, use the effect of "Ragigura" to add it to your hand. Then, Tribute "Faultroll" for this card's effect, before Special Summoning the "Faultroll" in your hand. Repeat until victory.
Note: The player needs to control at least 2 "X-Saber" monsters to Special Summon "XX-Saber Faultroll", so in reality, the player will need to control an additional "X-Saber" monster that is not "XX-Saber Faultroll".
Additional requirements: Control 2 copies of "Gigaplant".
Loop: For this card's effect, Tribute 1 "Gigaplant" that has already used its Special Summon effect, then use the effect of the other "Gigaplant" to revive that "Gigaplant". Repeat until victory.
Additional requirements: Control at least 1 copy of "Il Blud", with the other 2 copies in your Graveyard or already on your field (any combination).
Use the effects of the copies of "Il Blud" to ensure you control all 3, then use 2 of them (which have used their effects already) to Xyz Summon "Constellar Ptolemy M7". Tribute the Xyz Monster for this card's effect. Repeat until victory, except with the extra step of using the effect of an additional "Constellar Ptolemy M7" to return the copy in your Graveyard to the Extra Deck, which ensures you always have a Rank 6 Xyz Monster to Summon.
"Dewloren, Tiger King of the Ice Barrier" + "Grandsoil the Elemental Lord"
Loop: If you haven't already, Special Summon "Grandsoil the Elemental Lord" and use its effect to Special Summon "Dewloren, Tiger King of the Ice Barrier". Use the effect of "Dewloren" to return "Grandsoil" to the hand, then Tribute "Dewloren" for this card's effect. Repeat until victory.
With "Imperial Iron Wall" active, "Quillbolt Hedgehog" in the Graveyard and "Cannon Soldier" and at least 1 Tuner monster on the field, activate the effect of "Quillbolt Hedgehog" which Special Summons it. Tribute it with "Cannon Soldier" and "Imperial Iron Wall" prevents it from being banished. Repeat until victory.
If you have 1 Tuner monster on your Field and 2 "Quillbolt Hegehogs" in your graveyard, Normal Summon "Cannon Soldier" and revive your two "Quillbolt Hedgehogs", then overlay them for a rank 2 Xyz Monster. Tribute that rank 2 Xyz Monster for 500 damage. Since the 2 "Quillbolt Hedgehogs" were used to Xyz summon, they go to the graveyard. Repeat this with 11 more rank 2 Xyz monsters in your extra deck to do 6000 total damage, then revive your two Quillbolt Hedgehogs once again and tribute them, your Tuner Monster, and "Cannon Soldier" itself to do 2000 more damage for victory.
With 1 "Wind-up Rat" on your field and one in your graveyard, normal summon "Cannon Soldier" and activate "Final Attack Orders" or "Level Limit - Area A" or "All-Out Attacks". Use the 1st "Wind-up Rat" on your field to revive the 2nd "Wind-Up Rat" in your graveyard (both are switched to attack mode via "Final Attack Orders", "Level Limit - Area A" or "All-Out Attacks") and use Cannon Soldier's effect to tribute the 1st "Rat" to do 500 damage. Use the 2nd "Rat" to revive the 1st "Rat", then tribute the 2nd "Rat", repeat until victory.
With 1 "Spear Cretin" in the Graveyard, one face-down or recently flipped face-up on the field and an active "All-Out Attacks", Summon "Cannon Soldier" and Tribute the "Spear Cretin". Revive the other "Spear Cretin" in face-down Defense Position. "All-Out Attacks" causes it to be flipped face-up because it was Special Summoned. Repeat until victory.
Activate "Fusion Gate" and "Chain Material", then Summon "Cannon Soldier". Using "Chain Material" and "Fusion Gate", Fusion Summon "Elemental HERO Electrum" from your Extra Deck. "Elemental HERO Electrum" returns its banished Fusion Material Monsters to your Deck. Tribute it for "Cannon Soldier", then use "Fusion Gate" and "Chain Material" to Summon another. Since the first "Elemental HERO Electrum" was banished by "Dimensional Fissure" or "Macro Cosmos", it is returned to your Extra Deck, along with the Fusion Material Monsters, when the second is Summoned. Repeat until victory.
With "Ultimate Offering" activated, you can fill up the field with one "Cannon Soldier" and four Gadgets of any color. Then you can start activating the effect of "Cannon Soldier" to Tribute four of those Gadget and deals 2000 damage to your opponent then re-summons those Gadgets. Do this loop until the fifth Gadget is sacrificed and four other gadgets still exist on the field, you may have dealt 2500 damage to your opponent. enter the battle phase, clear out the opponent's monsters by using card such as "Lightning Vortex" and attack him/her with all of your monsters then you may have dealt around 8000 damage. If your opponent still breathing, tribute all of your monsters using the effect of "Cannon Soldier" to deal another 2500 damage.
When your LP are equal to or more than your opponent's, use "Ultimate Offering" to Summon "Black Ptera" and "Cannon Soldier", then Tribute "Black Ptera". "Black Ptera" returns to your hand as it was sent to the Graveyard, but not by battle. Summon again with "Ultimate Offering" and repeat until victory. If your Life Points are less than 500 points more than your opponent's, tribute "Cannon Soldier" itself at the end of this loop for victory.
You could also combine this with some "Nimble Momongas" to help boost your LP. If you have a "Mysterious Puppeteer" on your side of the field you only need to have LP greater than 500.
With "Dewloren" in your graveyard and "Spell Economics" on your field, normal summon Cannon Soldier and play "Premature Burial" to revive Dewloren from your graveyard (paying no life points due to Spell Economics). Use Dewloren's effect to return Premature Burial to your hand, then tribute Dewloren for 500 damage. Repeat until victory.
With "Dark Magician of Chaos", "Spell Economics" and "Cannon Soldier" on the field and "Dimension Fusion" in your hand, Tribute "Dark Magician of Chaos" with "Cannon Soldier". Activate "Dimension Fusion", paying no Life Points due to the effect of "Spell Economics", Special Summoning "Dark Magician of Chaos". Add "Dimension Fusion" to your hand with the effect of "Dark Magician of Chaos" and repeat until victory.
With "Imperial Iron Wall" and "Card of Safe Return" active, "Cannon Soldier" on the field and "Plaguespreader Zombie" in the Graveyard, activate the effect of "Plaguespreader Zombie", return 1 card from your hand to the top of your Deck and Special Summon it. "Card of Safe Return" causes you to Draw the card you just returned to your deck. Tribute "Plaguespreader Zombie" for "Cannon Soldier", while "Imperial Iron Wall" prevents "Plaguespreader Zombie" from being banished. Repeat until victory.