If your opponent controls a monster and you control no monsters, you can Special Summon this card (from your hand). Once per turn, if a monster(s) with ATK higher than this card is Special Summoned to your opponent's field (except during the Damage Step): You can make this card gain 700 ATK until the end of this turn.
Can only be Special Summoned when you control no monsters.
ATK boost is only applied when your opponent Special Summons a powerful monster.
Special Summoning a monster from your hand, when you control no monster is an effect shared by some other monsters. These monsters are splashable to many decks to give easy field presence and a body you can use for tribute or synchro plays. Lord Gaia the Fierce Knight distincts itself by being the only level-7 and having the highest ATK among them.
Here are some monsters you can pair with a Special Summoned Lord Gaia the Fierce Knight to make a Synchro monster. Mostly you want to use a level-1 Tuner to make a wide variety of level-8 Synchros, but level-9 also has some good monsters.