Is there a meaningful difference between giving a monster multiattack and giving it multiple turns per round?

I’m creating a CR21 boss for my medium-level party of six players to fight. I know that action economy is a big disadvantage for a single enemy fighting an entire party, so I’m giving the boss the ability to attack 4 times per turn (20-35 damage per most attacks).

I know the most common way to give a creature multiple attacks is to give it Multiattack, an action that allows it to use its attack abilities several times in one go. I’m considering instead rolling initiative for the boss 4 times and giving it a whole turn for each initiative value, giving it 4 separate attacks.

Will this have a significantly different effect on the battle than giving the boss a standard multiattack?


A couple thoughts I’ve had:

  • This allows the boss to use more bonus actions per round. The boss I’m designing doesn’t have any nonstandard bonus actions, so I don’t think this will make a big difference.
  • This allows the boss to move more often. I’ve divided the speed I want the boss to have by the number of turns it gets per round, so its total movement per round will be the same.
  • This gives the boss more reactions. I can see this making it quite a but more difficult. I’m not planning on using many reactions when I play the boss, though.