Note that the second effect of this card is not limited to once per turn. As long as it can attack more than once, it can become a potential OTK as each attack will deal at least 2800 damage.
With "ZW - Leo Arms", if your opponent controls more than 1 monster: its ATK will increase to 5800 and deal up to 5800 damage with its ATK-gaining effect. Send "Leo Arms" to the Graveyard and attack for 2800 damage; 5800 + 2800 = 8600.
With "ZW - Asura Strike", if your opponent controls at least 3 monsters: its ATK will increase to 3800, and it will be able to attack all 3 of your opponent's monsters, using this card's effect to make its full ATK dealt as damage. 3800 + 3800 + 3800 = 11400.
With "Shark Fortress": With its effect, this card can attack twice and deal 2800 x 2 = 5600 damage, regardless of the number of monsters your opponent has. If you cleared the field with this card, attack with "Shark Fortress" and deal 5600 + 2400 = 8000 damage.
Equipping this card with "Twin Swords of Flashing Light - Tryce" would allow your monster to attack twice. If you use this card's effect twice, its ATK-gain effect will carry across (until the end of the turn).