This card works well with "Trickstar" Decks, since they heavily rely on Special Summons, even more if you happen to run into an opponent who also uses Trickstars or a Fairy based Deck.
Using "Celestial Transformation" on an "Athena" and activating "Inferno Reckless Summon" while you control any other Fairy-Type monster can deal up to 6000 damage (this is done by first inflicting 600 damage with the first "Athena" when two copies are Summoned, and then 1800 damage with each "Athena" (thus, 5400 damage) by using each the second effect of "Athena" to Tribute the 4th Fairy you have and Summon another from the grave, triggering their first effect). If you Normal Summon a Fairy-Type monster after 3 "Athena" are on the field you can deal another 1800 damage, a total 7800 damage. To finish the opponent completely, if you have gathered 2 Level 4 Fairy-Types, Xyz Summon "Fairy Cheer Girl". If you only have 1 Fairy-Type, you can also Xyz Summon "Number 7: Lucky Straight" with "Athena" to Special Summon her again whith his bonus skill (16.67% chance) to finish the game or Xyz Summon "Number 11: Big Eye" to take control of one opponent monster to Xyz with your Fairy, for example "Gagaga_Cowboy"
This tactic works especially well in "Trickstar" Decks, since they heavily rely on Special Summons and burn effects:
If you have "Trickstar Lilybell" you can attack your opponent directly in addition to the 7800 Damage for an OTK
If you have "Trickstar Lycoris" she will burn the remaining 200 Life Points in your opponents next Draw Phase without the risk of triggering a trap when attacking
Combo it with "Trickstar Lilybell"'s effect for 4000+ Damage: Summon Lilybell, attack directly (800 Damage), get "Trickstar Lycoris" from your grave, use the effects of both to Special Summon them, activate IRS and summon 2 more Copies of Lilybell, attack directly again (3200 Damage) and get back lots of Trickstars from your grave. Optionally you can summon more Lycoris for later burn damage and/or attack with them.
Special Summon "Trickstar Lycoris" with "Celestial Transformation" (or other effects if your opponent decreases the ATK of your monsters so that she has 1500 or less ATK when summoned), then activate IRS. Now you will make 3 times the burn damage with cards like "Trickstar Reincarnation". Since those are Quick Spell cards, you can activate them in your opponents turn/Draw Phase. With just "Celestial Transformation" you can still summon Lycoris at the right time for some extra burn damage, for example when your opponent activates cards like "Card of Demise".
While this card is on the field, continuously attack your opponent's 1500 ATK or higher monsters with "Shining Angel" and "Nova Summoner". After you've cycled through all 6 of these cards in your Deck, activate the effect of "Athena" to Tribute the LIGHT Fairy-Type monster to Special Summon a "Shining Angel" or a "Nova Summoner" in your Graveyard. You will deal 3600 damage with the effect of "Athena" through this combo.
Special Summon "Athena" from your hand by the effect of "Valhalla"; Normal Summon "Meltiel, Sage of the Sky", then Tribute it to activate the effect of "Athena", and Special Summon "Darklord Superbia" from the Graveyard. Special Summon "Meltiel" from the Graveyard by the effect of "Superbia", then attack. If your opponent activates an effect, negate it using "Divine Punishment", gain 1000 LP and destroy 1 card by the effect of "Meltiel".
This combo will give you 2 strong monsters and inflict, at least, 1200 damage to your opponent. After the triple attack, you will have dealt up to 8300 damage.
If you want one more monster and 600 more damage, activate "Celestial Transformation".
You can send a "Radiant Jeral" from your side of the field to Special Summon another "Radiant Jeral" in your Graveyard with the effect of "Athena" while "The Sanctuary in the Sky" is on the field to increase your LP by 1000 points each turn and fulfill the requirements of Fairy-Type monster like "The Agent of Force - Mars", "The Agent of Judgment - Saturn", "Ancient Sacred Wyvern" or "Neo-Parshath, the Sky Paladin". They all need you to have higher Life Points than your opponent.
Using "Valhalla, Hall of the Fallen" to Special Summon "Athena" could be done after Special Summoning other monsters with "Valhalla". If you Special Summon a "Guardian Angel Joan", you have a 2800 beatstick as well as an easy way to gain LP. If "Joan" is destroyed, "Athena" can be Special Summoned and bring back "Joan" from the Graveyard. You will have gotten rid of whatever resources your opponent had that destroyed "Joan" (and may have destroyed "Athena" if you Summoned it first). If you gain LPs using the effect of "Joan", it will be easier to use the effect of "The Agent of Force - Mars" or related cards.
Use "Valhalla, Hall of the Fallen" to bring this card out on the first turn and "Foolish Burial" to send a powerful Fairy (like "Arcana Force XXI - The World") to the Graveyard. You can still Normal Summon so Summon a Fairy-Type monster and use this card to send it to the Graveyard to bring back the powerful Fairy (and do 1200 damage to your opponent with the effect of "Athena").
You can use the above combo using your Normal Summon to Summon "The Agent of Creation - Venus" then use its effect to Special Summon 3 "Mystical Shine Balls" and Tribute one for the effect of "Athena" to Special Summon "Arcana Force XXI - The World". If your opponent's field is clear, the total damage will be 8300 battle damage and 3000 points of effect damage.
While "The Sanctuary in the Sky" and "DNA Surgery" (selecting Fairy-Type) are active, attack an opponent's monster with 3 copies of multiple searchers to inflict massive damage. An order that would work for this is "Nova Summoner", "Shining Angel", "UFOroid", "UFO Turtle", "Masked Dragon" and finally "Troop Dragon". If you have enough copies of the monsters, you can win the game like this.
In fact, having "DNA Surgery" (Fairy) and "Athena" on the field means that your opponent will be taking 600 damage each time either player Summons a monster.
Use the above combo with one "Spear Cretin" in the Graveyard and one face-down on the field. On your turn, Flip Summon "Spear Cretin" and Tribute it via the effect of "Athena" to Special Summon a Fairy-Type monster in your Graveyard and use the effect of "Spear Cretin" to Special Summon the other "Spear Cretin". Your opponent takes 1200 to 1800 damage depending on the position of the monster they Summoned. You can use this method to swarm the field with Fairy-Type monsters. Just watch out for monsters like "Snowman Eater" that your opponent may bring back. You can limit their options with a "Soul Release".
This card can be an extremely powerful asset in an "Arcana Force" Deck. It not only damages the opponent for each "Arcana Force" monster Summoned, but also has the ability to send the monster to the Graveyard and reincarnate it for a second chance at the coin toss.
You can perform a OTK if you have "The Agent of Creation - Venus", "Hecatrice" and "Athena" in your hand as well as any field clearing spells such as "Heavy Storm", "Nobleman of Crossout" or "Fissure". First, fetch a "Valhalla, Hall of the Fallen" with "Hecatrice" and then use the "Valhalla" to Special Summon "Athena" and then follow up by Normal Summoning "Venus" and pay 1500 Life Points to Special Summon 3 "Mystical Shine Balls". Use the Special Summoning effect of "Athena" and Tribute a "Mystical Shine Ball" to Special Summon "Hecatrice" and the damage from the effect of "Athena" will total 3000 at this point. After that, by using the appropriate Spell Cards ("Lightning Vortex" and "Nobleman of Crossout" in most cases), you can clear the field and land direct attacks with all the monsters (2600 + 1500 + 1600 + 500 + 500 = 6700) to inflict a total of 9700 points of damage.
"Darklord Asmodeus" and "Darklord Superbia" have a lot of synergy with this card. "Asmodeus" can send any Fairy-Type monster from your Deck the Graveyard to be brought back with the effect of "Athena". "Superbia", when Special Summoned from the Graveyard, can Special Summon another Fairy-Type monster with it, giving you extra burn damage and an extra 2900 ATK beatstick in addition to the monster that you would have brought back anyway.
Additionally, you can use "Darklord Asmodeus" and other card effects to mill 2 "Athena" and "Darklord Superbia". When you have the third "Athena" on the field, you can Summon a Fairy-Type monster and then Tribute it with the effect of "Athena". Summon "Superbia", then use its effect to Summon "Athena" and repeat using "Superbia" as the Tribute. After you finished using this effect, you will have 3 "Athena" on the field, "Superbia" and any Fairy-Type monster from your grave on the field, and dealing 7800 damage in total. And with "Superbia" and 3 "Athenas" on the field, it's not hard to deal damage to the opponent.
When you Normal Summon "Majestic Mech - Ohka" or "Majestic Mech - Goryu" with their effects while you have a Fairy-Type monster in your Graveyard, you can send them to the Graveyard and then re-Summon them with the effect of "Athena" to get around their self-destruct effect.
While this card is on the field, and previously have set "Localized Tornado", attack your opponent's 1500 ATK or higher monsters with "Shining Angel" and/or "Nova Summoner". After you've Special Summon the 6th of these cards from your Deck, activate "Localized Tornado" to Shuffle the other 5 in your Graveyard back into the Deck, continue attacking. You will deal 8000 damage with the effect of "Athena" through this combo.
Use "Athena", "Brionac, Dragon of the Ice Barrier" and "Archlord Kristya" to perform OTK. First, you must have "Athena" and "Brionac" on your side of the field. Then you have to Special Summon "Kristya", return a Fairy-Type monster from your Graveyard to your hand and use the effect of "Brionac" (discard a Fairy-Type monster) to return "Kristya" to your hand. Special Summon "Kristya" and repeat the cycle-your opponent will lose 600 Life Points each time "Kristya" is Special Summoned.
Use this card in conjunction with "Honest" with its return to hand effect and "Ultimate Offering" to continually Summon it, dealing 600 damage, to create an OTK. See Athena OTK for tips on this OTK.