As long as the probability isn't zero, they can't gamble on it; they can't afford it.
Emperor Yan will certainly dispatch people to intercept, while Jiang Li will surely send additional manpower to annihilate the enemy. Jiang Li wants to issue a challenge letter because once action starts, it cannot be hidden from others, and secondly, to force the opponents to fight and kill their available manpower.
Though the Great Venerable is dead, the Heavenly Charm Demon God is still present, and so is the Heavenly Peng Demon God, along with the Drought Demon… or rather, the Imperial Daughter Ba, who is also still around.
On the Buddhist side, Shakyamuni Tathagata is currently unable to make a move, but Medicine Tathagata is still around.
Jiang Li intends to make the opponent push all their pieces to the forefront, both sides battling for a final victory.
