Gold will be your limitation very quickly.
You’ll need money for everything, dungeon, equipment, level.
Yes at low level, everything is cheap but as you progress you’ll find that a single piece of gear will required 3500 gold to level, and a hero level will cost you 17 000 gold.
As a counter part, the gold you get from dungeons and stuff doesn’t increase all that much… my 4hour free chest barely gives me 100g (and i finished the campaign). The secret room chest gives me 300. And most rewards are gear and not gold…
Most of my gold comes from quest reward (1000g if i am lucky, way less the other way around), and selling gear (which is counter productive in the sence that you require this equipment to level and increase the strenght of your heroes).
So yeah there isn’t a limitation as per energy or stamina, but you’ll find that grinding 24/7 for exp on dungeons will become horrible for almost no reward at the end.
A 8-9min run of the hidden forge (third dungeon) gives me 150 exp and i need about 200 000 exp to level. soo yeah GRIND baby GRIND!