Something to note is that to make this setup 100% reliable, the MC has to use the skill "Sentinel" to take the hits and most importantly the debuffs away from the rest of the party. This strategy relies on Ray having enough speed to cast immortality before the buff runs out, and both Alice and Juggernaut have a speed down debuff move that bypasses all resistances. Juggernaut can also hemorrhage Ray or Bessie, which kills them in a way that bypasses their equipment. The MC doesn't have to care about those since he'll be immortal, and he should always have the occasion to refresh Sentinel since it's a five turn buff. Also also Juggernaut has a move that can bypass one, and only one, defensive skill, which will kill Ray or Bessie if it hits them raw. If Sentinel is up, then it will bypass Sentinel but not the survival effect Ray and Bessie have, keeping them alive.