Creature Bank

Creature Bank is a collective term for the Adventure Map locations where a hero may fight against guards in order to receive a reward. The reward typically consists of gold and resources, but may also contain creatures or artifacts. The combat against the guards is a unique arrangement, where the hero's troops are located in the middle of the battlefield surrounded by enemies and war machines are not available. As with other battles, slain enemies do not respawn (should the hero retreat or be defeated). Visiting crypts or shipwrecks whose guards have already been defeated, decreases morale by -1 until the next battle.

Note the shown experience is based on the total HP of guards to be defeated, not as a separate reward.

Naga Bank gives sulfur, which may be considered as illogical as there are three other creature banks that are coherent with the magical resource they hold and the town they represent. These three are:

Dwarven Treasury guarded by dwarves from Rampart and holding crystal
Imp Cache guarded by imps from Inferno and holding mercury
Medusa Stores guarded by medusas from Dungeon and holding sulfur

The Heroes 3 HD mod addresses this by changing the Naga Bank reward from sulfur to gems. This behavior can be toggled off by unchecking the HD+ checkbox.

Creature banks

Creature banks (Shadow of Death)
Object	Guards	Reward
Object	Guards
Crypt	30 %: x30, x20,			1500							480	Terrain: grass, dirt, snow, swamp, sand Value: 1000 When visited after the guards have been defeated decreases the hero's morale by 1 for the next battle.
	30 %: x25, x20, x5,			2000							540
	30 %: x20, x20, x10, x5		t	2500							750
	10 %: x20, x20, x10, x10		t	5000							900
Cyclops Stockpile	30 %: x20,				4	4	4	4	4	4	1400	Terrain: any dry land Value: 3000 50% probability for 1/5 of the guards to be Cyclops Kings.
	30 %: x30,				6	6	6	6	6	6	2100
	30 %: x40,				8	8	8	8	8	8	2800
	10 %: x50,				10	10	10	10	10	10	3500
Derelict Ship	30 %: x20,			3000							600	Terrain: water Value: 4000 When visited after the guards have been defeated decreases the hero's morale by 1 for the next battle.
	30 %: x30,		t	3000							900
	30 %: x40,		t	4000							1200
	10 %: x60,		m	6000							1800
Dragon Fly Hive	30 %: x30,	x4									600	Terrain: any dry land Value: 9000
	30 %: x45,	x6									900
	30 %: x60,	x8									1200
	10 %: x90,	x12									1800
Dragon Utopia	30 %: x8, x5, x2, x1		t, m, M, R	20 000							3140	Terrain: any dry land Value: 10000
	30 %: x8, x6, x3, x2		m, M R x2	30 000							3870
	30 %: x8, x6, x4, x3		M R x3	40 000							4420
	10 %: x8, x7, x6, x5		R x4	50 000							5700
Dwarven Treasury	30 %: x50,			2500						2	1000	Terrain: any dry land Value: 2000 50% probability for 1/5 of the guards to be Battle Dwarves.
	30 %: x75,			4000						3	1500
	30 %: x100,			5000						5	2000
	10 %: x150,			7500						10	3000
Griffin Conservatory	30 %: x50,	x1									1250	Terrain: any dry land Value: 2000 50% probability for 1/5 of the guards to be Royal Griffins.
	30 %: x100,	x2									2500
	30 %: x150,	x3									3750
	10 %: x200,	x4									5000
Imp Cache	30 %: x100,			1000			2				400	Terrain: any dry land Value: 5000 50% probability for 1/5 of the guards to be Familiars.
	30 %: x150,			1500			3				600
	30 %: x200,			2000			4				800
	10 %: x300,			3000			6				1200
Medusa Stores	30 %: x20,			2000				5			500 (520)	Terrain: any except subterranean and water Value: 1500 50% probability for 1/5 of the guards to be Medusa Queens.
	30 %: x30,			3000				6			750 (780)
	30 %: x40,			4000				8			1000 (1040)
	10 %: x50,			5000				10			1250 (1300)
Naga Bank	30 %: x10,			4000				8 *			1100	Terrain: any dry land Value: 3000 *Sulfur is replaced by gems in HD mod and HotA 50% probability for 1/5 of the guards to be Naga Queens.
	30 %: x15,			6000				12 *			1650
	30 %: x20,			8000				16 *			2200
	10 %: x30,			12000				24 *			3300
Shipwreck	30 %: x10,			2000							180	Terrain: water Value: 2000 Can be visited without a boat if placed next to the dry land. When visited after the guards have been defeated decreases the hero's morale by 1 for the next battle.
	30 %: x15,			3000							270
	30 %: x25,		t	4000							450
	10 %: x50,		m	5000							900

Horn of the Abyss creature banks

Creature banks (Horn of the Abyss)
Object	Guards	Reward
Object	Guards
Ancient Altar	100 %: x25		R						7500	Terrain: any dry land Value: 20000 The reward is always Horn of the Abyss. If the bank has been defeated, the Horn of the Abyss on the exterior disappears. Does not appear on random maps unless it is enabled in the template settings.
Beholders' Sanctuary	30 %: x50,		m	3000					1100	Terrain: water Value: 2500 50% probability for 1/5 of the guards to be Evil Eyes.
	30 %: x75,		m	5000					1650
	30 %: x100,		M	6000					2200
	10 %: x150,		M	9000					3300
Black Tower	30 %: x1,		m	2000					180	Terrain: any dry land Value: 1500
	30 %: x1,		m	2250					180
	30 %: x1,		m	3500					250
	10 %: x1,		m	3750					300
Churchyard	100 %: x90		m	2500					1800	Terrain: any dry land Value: 1500 When visited after the guards have been defeated decreases the hero's morale by 1 for the next battle.
Experimental Shop	30 %: x20,	x1							900	Terrain: any dry land Value: 3500
	30 %: x40,	x2							1800
	30 %: x60,	x3							2700
	10 %: x80,	x4							3600
Ivory Tower	30 %: x35,	x3							1050	Terrain: sand, snow Value: 7000 Does not appear on random maps unless it is enabled in the template settings.
	30 %: x50,	x6							1500
	30 %: x65,	x9							1950
	10 %: x80,	x12							2400
Mansion	30 %: x40,		M	2500	2	2	2	2	1600	Terrain: any dry land Value: 5000
	30 %: x60,		M	5000	3	3	3	3	2400
	30 %: x80,		M	7500	4	4	4	4	3200
	10 %: x100,		M	10000	5	5	5	5	4000
Pirate Cavern	30 %: x20, x20,	x1							600	Terrain: rough Value: 3500 50% probability for 1/2 of Pirates to be Corsairs. Does not appear on random maps unless it is enabled in the template settings.
	30 %: x40, x40,	x2							1200
	30 %: x60, x60,	x3							1800
	10 %: x80, x80,	x4							2400
Red Tower	30 %: x35,	x1							1225	Terrain: any dry land. Value: 4000 Limit per zone: 1 50% probability for 1/5 of the guards to be Energy Elementals.
	30 %: x70,	x2							2450
	30 %: x105,	x3							3675
	10 %: x140,	x4							4900
Ruins	30 %: x20, x3, x3, x10 1			1000					328	Terrain: highlands Value: 1000 After defeating the guards, the shroud is removed from all tiles within 12 tiles from Ruins.
	30 %: x30, x5, x5, x10 1			2000					460
	30 %: x40, x7, x7, x20 2			3000					692
	10 %: x50, x9, x9, x20 3			4000					864
Spit	30 %: x16,			3000					560	Terrain: swamp Value: 1500 Does not appear on random maps unless it is enabled in the template settings.
	30 %: x24,			4500					840
	30 %: x32,			6000					1120
	10 %: x48,			9000					1680
Temple of the Sea	30 %: x8, x6, x3, x2		t x2 m, R	10 000					3830	Terrain: water Value: 10000
	30 %: x8, x7, x4, x3		t, m, M, R	15 000					4560
	30 %: x8, x7, x5, x4		m M x2 R	20 000					5110
	10 %: x10, x9, x6, x5		M x2 R x2	30 000					6370
Wolf Raider Picket	30 %: x50,	x4							500	Terrain: any dry land Value: 9500
	30 %: x75,	x6							750
	30 %: x100,	x8							1000
	10 %: x150,	x12							1500

Guards preview table

The table shows how to pre-check the guard strength of an object without attacking it.
Guarding stacks accentuated with bold font should be considered in the first place.
Stacks insignificant for a preview are omitted.
The overall amount of creatures can be checked in the status bar (above the resource line at the bottom of the screen) by hovering over an object already visited (not attacked) by a hero.

Guards	Stacks	Guards preview	Upgraded stack
Cyclops Stockpile
30 %: x20	4 x5	lots (20-49) of Cyclopses	pack (10-19) of Cyclopses few (1-4) Cyclops Kings
30 %: x30	6 x5		lots (20-49) of Cyclopses several (5-9) Cyclops Kings
30 %: x40	8 x5		lots (20-49) of Cyclopses several (5-9) Cyclops Kings
10 %: x50	10 x5	horde (50-99) of Cyclopses	lots (20-49) of Cyclopses pack (10-19) of Cyclops Kings
Dragon Fly Hive
30 %: x30	6 x5	lots (20-49) of Dragon Flies	No
30 %: x45	9 x5	lots (20-49) of Dragon Flies
30 %: x60	12 x5	horde (50-99) of Dragon Flies
10 %: x90	18 x5	horde (50-99) of Dragon Flies
Dragon Utopia
30 %: x8, x5, x2, x1		pack (10-19) of creatures	No
30 %: x8, x6, x3, x2		pack (10-19) of creatures
30 %: x8, x6, x4, x3		lots (20-49) of creatures few (1-4) Black Dragons
10 %: x8, x7, x6, x5		lots (20-49) of creatures several (5-9) Black Dragons
Dwarven Treasury
30 %: x50	10 x5	horde (50-99) of Dwarves	lots (20-49) of Dwarves pack (10-19) of Battle Dwarves
30 %: x75	15 x5	horde (50-99) of Dwarves	horde (50-99) of Dwarves pack (10-19) of Battle Dwarves
30 %: x100	20 x5	throng (100-249) of Dwarves	horde (50-99) of Dwarves lots (20-49) of Battle Dwarves
10 %: x150	30 x5	throng (100-249) of Dwarves	throng (100-249) of Dwarves lots (20-49) of Battle Dwarves
Griffin Conservatory
30 %: x50	10 x5	horde (50-99) of Griffins	lots (20-49) of Griffins pack (10-19) of Royal Griffins
30 %: x100	20 x5	throng (100-249) of Griffins	horde (50-99) of Griffins lots (20-49) of Royal Griffins
30 %: x150	30 x5		throng (100-249) of Griffins lots (20-49) of Royal Griffins
10 %: x200	40 x5
Imp Cache
30 %: x100	20 x5	throng (100-249) of Imps	horde (50-99) of Imps lots (20-49) of Familiars
30 %: x150	30 x5		throng (100-249) of Imps lots (20-49) of Familiars
30 %: x200	40 x5		throng (100-249) of Imps lots (20-49) of Familiars
10 %: x300	60 x5	swarm (250-499) of Imps	throng (100-249) of Imps horde (50-99) of Familiars
Medusa Stores
30 %: x20	4 x5	lots (20-49) of Medusas	pack (10-19) of Medusas few (1-4) Medusa Queens
30 %: x30	6 x5		lots (20-49) of Medusas several (5-9) Medusa Queens
30 %: x40	8 x5		lots (20-49) of Medusas several (5-9) Medusa Queens
10 %: x50	10 x5	horde (50-99) of Medusas	lots (20-49) of Medusas pack (10-19) of Medusa Queens
Naga Bank
30 %: x10	2 x5	pack (10-19) of Nagas	several (5-9) Nagas
30 %: x15	3 x5	pack (10-19) of Nagas	pack (10-19) of creatures pack (10-19) of Nagas
30 %: x20	4 x5	lots (20-49) of Nagas	lots (50-99) of creatures few (1-4) Naga Queens
10 %: x30	6 x5	lots (20-49) of Nagas	several (5-9) Naga Queens

Horn of the Abyss guards preview table