For the adventurous, despite this card's erratum, it is still possible to FTK by Tributing a single monster whose Level has been boosted extremely high. Note that there is no rule preventing monster Levels from exceeding 12, unless the card explicitly says so.
One method to pull this off is with "Mecha Phantom Beast Hamstrat", whose effect Summons two "Mecha Phantom Beast Tokens". The Level of "Hamstrat" is increased by the Levels of all said "Tokens", so "Hamstrat" will be Level (3 + 3 + 3 =) 9. Activate two copies of "Galaxy Queen's Light". The first will boost all "Tokens" to Level 9, making the Level of "Hamstrat" (3 + 9 + 9 =) 21; the second will boost all "Tokens" to Level 21, making the Level of "Hamstrat" (3 + 21 + 21 =) 45. Tributing "Hamstrat" for the effect of this card will then inflict 9000 damage.
"Hermit of Prophecy" can boost its own Level indefinitely as long as there are "Spellbook" Spell Cards to activate. The effect of "The Grand Spellbook Tower" can aid this, as well as being a "Spellbook" Spell Card itself.
If not going for an FTK, two other ways to get a monster up to an extremely high Level include:
Two copies of "Photon Satellite" can quadruple their own Levels every turn. Two turns after both are on the field, their Levels will each be 64.
"Greed Quasar" can increase its Level by battling (though then the damage dealt by this card will likely be redundant).
Normal Summon "Black Salvo" and use its effect to get a Level 4 DARKMachine-Type monster to Synchro Summon for this card.
In a "Gimmick Puppet" Deck, the effect of "Salvo" can be used to Special Summon "Gimmick Puppet Des Troy" or "Scissor Arms", then tune both for this card. Then Tribute one of the many Level 8 monsters the Deck runs, and attack with this card. In one turn, this combo can inflict 4200 damage, if this card attacks directly.
In a Machine-only Deck running this card and the above "Black Salvo", the effect of the Level 8 "Gearspring Spirit" can instead be used to reduce an opponent's monster's ATK to 0, effectively allowing this card to deal direct damage. Add in "Solidarity" to boost this card's ATK by 800 and increase the potential damage output to 5000.
This card has an extremely high potential of creating an OTK situation, especially when utilizing a Deck that can swarm and attack relentlessly:
The following 3-card setup can Synchro Summon this card and clear the field at the same time to pave the way: Use "Advanced Ritual Art" to Ritual Summon "Demise, King of Armageddon" by sending any 2 of "Mechanicalchaser" or "Blocker", then clear the field with the effect of "Demise". Then Normal Summon "Black Salvo", use its effect to Special Summon one of the monsters sent by "Advanced Ritual Art" to Synchro Summon this card.
This card fits in quite well with the "Quillbolt Loop". An OTK requires any Tuner + "Imperial Iron Wall" + "Quillbolt Hedgehog". Activate the effect of "Quillbolt", Tribute it with the effect of "Dark Strike Fighter" while preventing the removal of "Quillbolt" with "Imperial Iron Wall".
This card can be very useful in a "Yubel Synchro" Deck, for a quick way to Summon, reborn a "Doom Shaman" and use its effect to Special Summon "Sinister Sprocket".
If this card and "Yubel" is on your field, use "DNA Surgery" and declare Machine to change "Yubel" into a Machine-Type monster, use "Machine Duplication" to Summon 2 more "Yubels", then tribute them all and this card to inflict 7400 points of damage.
If used in a "Fish Synchro" Deck, this card can be used for an OTK if there also "Superancient Deepsea King Coelacanth" on your field. Just attack with both of them directly and Tribute both using this card's effect for an OTK by LP deduction.
Use "DNA Surgery" and declare Plant to use the effect of "Copy Plant" for heavy effect damage. Add "Inferno Reckless Summon" with "Copy Plant" for extra damage.
"Black Ptera" and "Ultimate Offering" creates an OTK.* "Vylon" Tuner monsters that equips right after they leave the field can be Tributed. In a "Vylon" Loop, a One Turn Kill can pretty much be possible.
The following 1-card setup can OTK immediately if the opponent's field is clear: Normal Summon "Summoner Monk" and use its effect to Summon a second one from your Deck. Use the second "Monk" to Summon "Rescue Cat" from your Deck, then Tribute "Rescue Cat" to Summon two "X-Saber Airbellums" from your Deck. Tune each "Airbellum" with each "Summoner Monk" to Synchro Summon 2 "Dark Strike Fighters". Attack directly with both of them, then Tribute both for an OTK (2600 + 2600 + 7*200 + 7*200 = 8000).