Operation: Dart Storm (sometimes shortened to ODS, O:DS, or Dart Storm) is the fourth upgrade on the first path for the Monkey Ace in BTD6. It shoots 16 darts per volley and shoots darts and anti-MOAB missiles (from Fighter Plane) twice as quickly. Volleys of darts are shot every 0.63s instead of 1.26s, while the twin anti-MOAB missiles are shot every 2.0s instead of 4.0s. Additionally, anti-MOAB missile explosions deal 24 damage per missile instead of 18, and retains 4 pierce.
Operation: Dart Storm combines the potential of extra darts with improved anti-MOAB missiles, thereby making the Monkey Ace more reliable against both bloons and MOAB-class bloons. This makes it a decent upgrade for the mid-game, chipping down blimp health while also providing cleanup against bloons. Combining with Berserker Brew or Stronger Stimulant improve its dart damage to bloons by a large margin, thereby improving its overall reliability for the mid-game.
This upgrade is useful for wiping out many bloons on screen while also being a great option for beating MOAB-class bloons, especially for earlier rounds. On its own, it can wipe out the outer layers of regular MOABs and Fortified MOABs before Round 81 with ease.
The best crosspath is the 4-0-1 ODS, or 4-0-2 if there is exceptionally good central coverage on the given map. 4-2-0 is useful if camo detection is required, since ODS cannot detect camo without support unlike in BTD5 when it was the upgrade after Spy Plane.
Do not rely on a 4-2-0 Operation: Dart Storm to handle Camo Leads, as pineapples from the Exploding Pineapple upgrade are not deployed twice as fast and due to the random nature of pineapples in general.
Operation: Dart Storm hasn't changed very much since it was first released, since it already attacks anti-MOAB missiles fast enough to take down early MOABs with ease, but it is overall a little weaker versus single-target blimps. It also got indirectly buffed by a base Monkey Ace dart projectile size buff.