arr = [
{ id: 1, mana_cost: 4 },
{ id: 2, mana_cost: 6 },
{ id: 3, mana_cost: 8 },
{ id: 4, gold_cost: 6 },
{ id: 5, gold_cost: 10 },
{ id: 6, gold_cost: 2 }
]
arr = [
{ id: 6, gold_cost: 2 },
{ id: 1, mana_cost: 4 },
{ id: 2, mana_cost: 6 },
{ id: 4, gold_cost: 6 },
{ id: 3, mana_cost: 8 },
{ id: 5, gold_cost: 10 }
]