Economy

Castle Busters runs on a handful of resources. You earn Coins and Wood from battles and chests and spend them on units, castle blocks, wheels, and helpers. Gems are the premium currency for skipping timers. And Wild Cards turn into the unit cards you need to level a unit up.

For how these fit together and what to buy first, see Where to spend and Which units to build.

Currencies

Currency	What it is for
Coins	Soft currency. Earned from battles and chests; spent on unit upgrades, castle blocks, wheels, and helpers.
Wood	Building material. Spent alongside Coins to build and upgrade castle blocks and foundations.
Gems	Premium currency. Skips build and upgrade timers and buys shop offers.
Wild Cards	Convert into cards for a unit of the matching rarity. Come in Common, Uncommon, Rare, Epic, and Legendary, plus a universal Wild Card.

Upgrading units with cards

Every unit levels up with its own cards plus Coins. A unit’s rarity sets where its card levels begin and how steep they climb, but they all cap at level 20. Short on a unit’s cards? Wild Cards of its rarity fill the gap.

Rarity	Card levels	Upgrades	Total cards	Total Coins
Common	1–20	19	43,823	450.96K
Uncommon	3–20	17	43,821	450.96K
Rare	4–20	16	43,817	450.95K
Epic	6–20	14	43,800	450.90K
Legendary	10–20	10	43,600	450.10K

Here is the surprise: maxing any unit costs almost the same, about 43,600 to 43,823 cards. Rarity does not change the total, only the shape. A Common climbs 19 small steps from level 1; a Legendary takes 10 big ones from level 10. The real wall is collecting a specific unit’s cards, and rarer cards drop less often.

Card costs by rarity

The full cost of every card level, one table per rarity.

Common units

Levels 1 to 20.

Level	Cards	Coins
1	—	—
2	2	5
3	4	10
4	7	20
5	10	30
6	20	50
7	40	100
8	60	250
9	80	400
10	100	600
11	200	1,500
12	300	3,000
13	500	5,000
14	1,000	10,000
15	1,500	20,000
16	2,500	35,000
17	5,000	50,000
18	7,500	75,000
19	10,000	100.00K
20	15,000	150.00K

Uncommon units

Levels 3 to 20.

Level	Cards	Coins
3	4	10
4	7	20
5	10	30
6	20	50
7	40	100
8	60	250
9	80	400
10	100	600
11	200	1,500
12	300	3,000
13	500	5,000
14	1,000	10,000
15	1,500	20,000
16	2,500	35,000
17	5,000	50,000
18	7,500	75,000
19	10,000	100.00K
20	15,000	150.00K

Rare units

Levels 4 to 20.

Level	Cards	Coins
4	7	20
5	10	30
6	20	50
7	40	100
8	60	250
9	80	400
10	100	600
11	200	1,500
12	300	3,000
13	500	5,000
14	1,000	10,000
15	1,500	20,000
16	2,500	35,000
17	5,000	50,000
18	7,500	75,000
19	10,000	100.00K
20	15,000	150.00K

Epic units

Levels 6 to 20.

Level	Cards	Coins
6	20	50
7	40	100
8	60	250
9	80	400
10	100	600
11	200	1,500
12	300	3,000
13	500	5,000
14	1,000	10,000
15	1,500	20,000
16	2,500	35,000
17	5,000	50,000
18	7,500	75,000
19	10,000	100.00K
20	15,000	150.00K

Legendary units

Levels 10 to 20.

Level	Cards	Coins
10	100	600
11	200	1,500
12	300	3,000
13	500	5,000
14	1,000	10,000
15	1,500	20,000
16	2,500	35,000
17	5,000	50,000
18	7,500	75,000
19	10,000	100.00K
20	15,000	150.00K