"Where did he get the ability to attack the God Country of Slaughter and Death? Turns out, he found a powerful backer to rely on."
Everyone could tell at a glance that the entity capable of confronting the God of Slaughter and Death head-on was an Incarnation of Powerful Divine Power. Only an Incarnation of such power could directly oppose the master of a God Country from within, despite its God Level being lower than that of Slaughter and Death.
Though his Divinity Level might be inferior, his superior mastery of the Rules of Godhood was overpowering, akin to how a Level 70 player with no gear would still lose to a Level 60 player dual-wielding epic Wind Swords.