From Digimon Masters Online Wiki
Burst Mode is an additional evolution, equal or superior to Mega, that can be unlocked. These are called Side Mega or Burst Mode. Not all Mercenary Digimon have one. Below is a list of Digimon who can achieve Burst Mode/Side Mega.
- Mercenary Digimon must be at least level 65 and have the required item in their inventory.
- Partner Digimon (Agumon, Gaomon, Lalamon, Falcomon) must be at lvl 71 instead of 65 to achieve Burst Mode. Player must also accomplish a series of quests given by the BanchouLeomon NPC located at Infinite Ice Wall (aka, how badly do you really want Burst Mode?). The quests become available once your partner reaches level 65.
- When using Burst Mode/Side Mega, a varying number of Accelerator items are used each time. They can either be purchased from the Digicore Merchant Kamemon NPC, dropped by certain digimon (HerculesKabuterimon at Infinite Ice Wall is one), or received during Events.