Despite the flurry of thoughts and concerns about the situation possibly being another trap, John knew that under the current circumstances, he had no choice but to cooperate with the others to quickly eliminate Mystery Vanguard.
Without resolving this immediate threat, he wouldn't have the opportunity to investigate further.
After Duke Arsena had laid out their strategy, as a Paladin, he naturally took the lead in the attack.
With his formidable defensive capabilities, he was well-suited to withstand the frontal assaults of Mystery Vanguard.
This would allow the other three to launch a full-scale attack on Mystery Vanguard while it was distracted by Arsena.
Duke Arsena believed that the combined strength of John and Mystery Protector was formidable enough.
As long as their coordination was seamless, they could swiftly defeat Mystery Vanguard.