Stun Window:

1. Make sure you have EX Special ready before entering a stun window, and Blazing Heart active (The glowing rage bar under his avatar) \[and have Manual Stun on\]

2. Enter stun window with any agent EXCEPT Manato, preferrably a stunner agent with an EX special used to enter the stun window (proccing 4PC KOS buff)

3. Immediately pick Manato to CA, use his EX special and let him perform that ability for at least a second and a half to make use most of its damage hits. Simulatenously while he's performing that ability, switch to Lucia, press EX while holding BA to avoid immediately going into CA (Remember, you want Manato to perform that EX special animation for at least a second and a half) until she bonks the enemy with her hand. When you know she's about to bonk with her wand, that's when you click BA to trigger another CA

4. CA with Manato again, press E (Most of the time it should track close to the enemy; You want to do this to lose health to regain the CRIT RATE from his W-engine), and then ULT. Then just bash attack the enemy for the rest of the stun duration

  
Tips:

\- If you want to have the CRIT RATE passive up at the beginning of the stun window, you can also either perform Bash attack or Basic attack when enemy daze bar is at least 97% then switch to your stunner to perform the steps in the Stun Window

\- If you want Manato to KEEP ATTACKING while simulatenously using your stunner and support's resources, you should trigger Manato's 3rd Basic Attack, where he begins lifting himself up in the air, as he will continue to perform that action for the next 2 seconds. He's both immovable and invulnerable when performing this action, thus you can use to animation-cancel. When he performs this action, just immediately exhaust your stunner or support's EX abilities, and then immediately go back to him

Read description to utilize Manato's full potential during stun windows