Gold is one of the primary resources used within the game. It is used to upgrade most of the hero abilities, rank, mastery, and numerous others. It is obtained via completion of missions, gamemodes, and through various achievements.
Gamemodes in which gold can be earned in significant amounts:
Daily Mission (Gold & EXP Chip > M'kraan Shard = ISO-8 & Norn Stones)
Alliance Battle + Extreme Alliance Battle
Special Mission
Co-Op Play (The higher your VIP level, the higher the chance of getting more gold)
Villain Siege (All three missions; bonus characters for potentially bonus gold)
Gamemodes in which gold earned varies:
World Boss Invasion
Alliance Raid
Shadowland
Legendary Battle
Dimension Rift
Alliance Conquest (Rank rewards)
Timeline Battle (Rank rewards)
Epic Quest
Story Missions
Gamemodes that do not reward gold:
World Boss
World Boss Ultimate