Every other guide on this site answers a local question. Which currency to buy, when to promote, how to survive a Survivor run, whether a challenge is worth starting.
This one is about the thing underneath all of them. Injustice: Gods Among Us Mobile has an economy, that economy was designed by people who thought carefully about it, and once you can see the design, most progression decisions answer themselves — including the ones about money.
None of what follows is a complaint. A free game has to be built this way to exist at all. But the design is legible, and being able to read it is worth more than any individual tip.
Four currencies, one job each
The first thing to notice is that the currencies are not interchangeable, and that is deliberate rather than incidental. Each one blocks a different kind of progress.
| Currency | What it gates | How it is throttled | What happens when you have lots |
|---|---|---|---|
| Power Credits | Levelling characters and gear | Abundant, earned constantly | Nothing — it was never the constraint |
| Nth Metal | Promotion, chests, rerolls | Deliberately slow trickle | Real progress, which is the point |
| Alliance Coins | The alliance store only | Depends on other people | Possibly nothing, if your alliance is dead |
| Energy | How often you can do anything | Regenerates to a cap, then stops | Impossible — that is what a cap means |
Read the right-hand column downward. That is the design.
A single-currency game has an obvious failure mode: accumulate enough of the one resource and you are unblocked everywhere. Four currencies with separate jobs means being rich in one tells you almost nothing about whether you can progress. You can sit on a fortune in Power Credits and be completely stuck, which is a state that would be impossible in a simpler system.
Two throttles: the tap and the gate
Underneath the four currencies there are only two mechanisms doing the actual limiting, and they work in completely different ways.
The tap is Energy. It rate-limits everything. Every other resource is downstream of attempts, and attempts regenerate at a fixed rate up to a ceiling. This is why the game is time-gated rather than effort-gated: playing harder does not increase the flow, only playing more often does — and only up to the point where you are no longer letting the tap overflow.
The gate is shards. Promotion shards, gear shards, the materials that come from Phantom Zone and challenge rewards. These cannot be reached with the abundant currency at all. No quantity of Power Credits converts into a promotion.
That distinction explains an enormous amount. A tap can be waited out — leave it running and it fills. A gate cannot. It opens for a specific key or it does not open, and the keys come from a small number of named sources, several of which run on the game's schedule rather than yours.
Almost every "I am stuck" post in this game is someone standing at a gate, holding a full bucket of the wrong thing.
Why progress feels smooth and then stops
Here is the shape of the curve, and it is the most important structural fact in the game.
Levelling is continuous. It improves in small increments, using a currency you earn constantly, with feedback every step. It feels like progress because it is progress, delivered smoothly.
Promotion is discrete. It happens in jumps, requires materials from limited sources, and pays nothing until the jump completes.
So the early game feels generous and frictionless — everything is levelling, and levelling always works. Then you arrive at a star tier and the machinery changes underneath you. Nothing got harder. The game started asking for a different kind of thing, and the habits that carried you through the first phase are useless in the second.
This is the wall that stalls most accounts, and people misdiagnose it constantly. They read it as "I need more power" and pour resources into levelling — the thing that is still working, still smooth, still not the constraint.
The discreteness pattern repeats
Once you have seen it at promotion, you see it everywhere. The game is built on thresholds that pay nothing until crossed.
Gear breakpoints. Upgrades accumulate, but the meaningful stat jumps land at specific thresholds. One upgrade short of a threshold is functionally close to not having upgraded at all.
Promotion tiers. Shards accumulate toward a jump that either happens or does not.
Challenge completion. Partial completion pays partial rewards, but the headline prize is binary. Seventy percent of a challenge is not seventy percent of the character.
The strategic conclusion is the same in all three cases and it is the most transferable rule in the game: finish one thing before starting the next. Spreading resources across several unfinished thresholds is the only way to spend everything and gain nothing, and it is the default behaviour, because starting is more satisfying than finishing.
The three pressure points
If you were designing a free game and needed spending to feel reasonable rather than coerced, you would place the offer at moments where a purchase genuinely solves a real frustration. This game does exactly that, and there are three of them.
1. The wall. You arrive at the promotion gate. Levelling has stopped helping. The shards come from limited sources. Currency converts directly into the thing standing in your way, and at that moment buying is the most rational-feeling decision available. It is also often correct — this is the pressure point where spending most reliably does what you hoped.
2. The window. A challenge is running, the deadline is real, and the resources needed to finish exceed what regeneration will supply in the days remaining. Deadline plus shortfall equals purchase. This is where the most money gets spent for the least permanent benefit, because the window closes whether or not you finished.
3. The near-miss. One upgrade from a breakpoint. One tier from a promotion. One fight from a reward. The remaining gap is small, the investment already made is large, and the arithmetic of "just finish it" is overwhelming in the moment. This is the most expensive of the three, because every individual near-miss purchase is small and defensible, and nothing tallies them for you.
Recognising which of these three you are standing in is most of the skill. The purchase is not automatically wrong at any of them — but the reason it feels compelling is structural, not personal, and knowing that is what lets you decide rather than react.
What the design implies about how to play
Five rules, all derived from the above rather than from taste.
Never let the tap overflow. Energy at cap is income that never arrived. Frequency beats duration, and this is arithmetic, not discipline. The daily routine guide turns it into a habit that takes two minutes.
Diagnose by shortage, not by holdings. What you have most of is not your problem. What you are short of is.
Finish thresholds; never spread across them. Gear, promotion, and challenges all pay on completion.
Take scheduled routes before on-demand ones. Challenges and events supply gate materials cheaply on their schedule; Phantom Zone supplies them expensively on yours. Use the cheap ones when they are open.
Decide during the calm, not at the pressure point. Pick your target in a weekly review, when nothing is urgent. The three pressure points are specifically designed to be poor moments for judgement, and the defence is having already decided.
Where we fit, honestly
We sell resources inside this economy, so it would be strange to pretend we are outside it. Two things worth saying plainly.
The design is also why the wrong purchase feels like nothing. Because the currencies are separated by function, buying the one that is not your constraint produces no visible change whatsoever. That is not a service failing you — it is four separate gates working exactly as intended. It is also the single most common reason people are disappointed after spending, with us or in the in-game store, and it is entirely preventable by diagnosing first. Are Injustice mods worth it? has the diagnosis table.
The honest case for spending is compression, not power. The tap runs at a fixed rate. Money buys weeks you could not otherwise compress, and nothing else. If the weeks were not what stood between you and what you wanted, no purchase helps.
If you have diagnosed the shortage and want to close it, currency, gear and characters are listed separately for exactly the reason this whole guide describes — they solve different gates. And are Injustice mods safe? covers the risk side before you order anything.
The short version
- Four currencies exist so no single resource can unblock your whole account.
- Whatever you have most of is not your bottleneck.
- Energy is the tap: it rate-limits everything and cannot be stockpiled.
- Shards are the gate: the abundant currency cannot reach them at any quantity.
- Levelling is continuous, promotion is discrete. The wall is a change in question, not in difficulty.
- Thresholds pay nothing until crossed. Finish one before starting the next.
- Money is designed to enter at the wall, the window, and the near-miss. Decide before you get there.
Where to go next
- Injustice Power Credits — the abundant currency, and what it genuinely cannot buy
- Injustice Nth Metal — the throttled one, and why the trickle is deliberate
- Injustice character promotion — the wall itself, in detail
- Injustice daily routine — how to stop the tap overflowing
- Are Injustice mods worth it? — diagnosing your shortage before spending on it
- Injustice account progression — the four phases this design produces
- Is Injustice pay to win? — the verdict this design actually supports
- The Injustice glossary — every term used above, defined plainly