1. Floors:

S-class Cosmo begins dropping from Titan Temple floor 5. Compared to floor 4, the only real difference in difficulty comes from the increase in numbers.

The enemy lineup will be: Titan + Golden Arrow Seiya + Pavo Mayura. The Titan will act first with an AoE attack as usual. When it drops below 40% HP, it will revive dead Saints and summon buffed monsters. If you cleared floor 4 without a hitch, and you're able to withstand Golden Arrow Seiya's single-target damage, then you're not far away from getting a perfect clear for this floor.

2. Strategy:

As the clear conditions include having more than 30% HP remaining and losing less than 3 Saints, bringing a healer is recommended.

As the boss will use a revival skill after dropping below 40% HP, it is recommended to just focus the Titan down so that you don't waste your damage skills on lesser targets.

Golden Arrow Seiya deals pretty high single-target damage and his SPD of 435 is quite high too. So, your Saints must be able to withstand 1 AoE from the Titan and one attack from Seiya. (Ensure this by leveling up your Saints and equipping them with Cosmo that increase their survivability)

It's also worth noting that Golden Arrow Seiya has two passive skills. The first is [God's Binding], which increases his attack by 6% after each attack. The second is [Cosmic Star Arrow], which fires a Cosmic Star Arrow at 1 enemy when he ends his turn after having 4 stacks of God's Binding. This makes it so that his damage increases the longer the battle drags on. If you don't have enough damage to quickly finish off the boss, crowd controlling Seiya isn't a bad idea.