You are earning them passively (after unlocking by holding a position in Legends Challenger Tournament in Arena of Heroes. The amount of your earning depends on your rank in the ladder. Players ranking at Champion ranks earn (400-rank + 1) Gladiator coins per hour (e.g. player ranked Champion 12 earns 389 Coins per hour). Players at lower positions earn fewer coins per hour.
Gladiator Coins rewards
|60 Athalia Soulstones||250,000|
|60 Ezizh Soulstones||250,000|
|60 Fawkes Soulstones||150,000|
|60 Numisu Soulstones||150,000|
|60 Ulmus Soulstones||150,000|
|60 Grezhul Soulstones||150,000|