Collaboration Stages · Stage 1Immortal Allen O'Neillオニ軍曹 アレン・オニール1★ 100%2★ 150%3★ 200%4★ 300%Data updated: 2026-07-2430Energy Cost4,230XP Reward10,000Enemy Base HP4,500Stage Length5Max Enemies1.2Difficulty Build a lineup for this stage Test your team vs this stageStage rewards1% — HYAKUTARO · first clear · Treasure RadarEnemy spawns (11)EnemyStrengthCountFirst SpawnRespawnBase HP TriggerNotesMARS PEOPLE (Enemy)100%56.7s16.7s100%—MARS PEOPLE (Enemy)100%130.7s—100%—MARS PEOPLE (Enemy)100%133.3s—100%—MARCO (Enemy)100%160s—100%—MARS PEOPLE (Enemy)100%180s—100%—MARS PEOPLE (Enemy)100%184s—100%—MARS PEOPLE (Enemy)100%∞100s20s~40s100%—MARS PEOPLE (Enemy)100%30s20s~40s90%—MARCO (Enemy)100%10.1s—90%—ALLEN O'NEIL (Enemy)100%10.1s—90%BossMs. Sign100%∞900s900s100%—All Metal Slug Defense stages