(To save time, I'm gonna state what all pieces can do)

Pawn: Swordsman, channels lightning through its sword that can be used in melee and long range. It also can channel lighting from the sky to strike at enemies.

Knight: Wields a spear. Able to chain enemies together, summon meteors that leaves the ground on fire, and summon phantom clones of itself that charges at enemies to disorient them. Really Fast as well.

Bishop: Also wields a spear. Summons fireballs that charges and explodes with large AoE, able to pull enemies in with Purple Fireballs. Long range continuous laser attack. Summons monsters that fight for her. Teleportation as well.

Rook: Just fists, and chases enemies constantly while leaving a trail of fire behind, able to spin rapidly and turn into a blazing tornado, able to enemies at range with its hands, summons fire attacks from the ground and able to fire two massive continuous beams of fire with its palms. Can fire gears from its body to amplify its speed and strength for a brief period of time.

Queen: Ice Sword. Able to teleport, freezes enemies, summon homing ice crystals that follows enemies, summon several swords of ice that slams down onto the ground, dealing a large AoE.

King: Staff. Summons magma fissures that has high AoE, fast homing fire missiles that target enemies, massive meteors that unleashes a shockwave and leaves fire behind. Summons a fire shield that makes it near invincible, and able to shoot out a long jet of fire with its staff.

Let's say there's 8 Pawns and one of the other pieces in this scenario

This dungeon appeared as a gate on SL Earth. What rank would it be? (And how many S Ranks would it take to defeat it)