Commander Legends is a weird peanut butter and jelly set, where peanut butter (Draft) and jelly (Commander, dont ask) combine their forces for a Magic experience like no other
Because of this, Lingering Souls was banned less than two months after its release
Efficiency can be determined simply by the reward you receive at certain mana costs (Counterspell and Cancel do the same thing, but Counterspell costs less), the total payoff you receive from a single card (Hull Breach and Decimate are both good cards, but Decimate usually covers much more ground), or the payoff you receive in conjunction with other cards (Anointed Procession makes other token production cards completely absurd if unchecked, which is usually better than adding one more card that simply makes tokens like Spectral Procession in a token strategy)
The line I'll draw is that the card has two distinct names, and they often, but not always, have two distinct arts
The last way white lends aid to your mana base is by helping you tutor (search your library) for lands (often Plains cards), and adding them to your hand
