The presence of the mana on the earth causes supernatural phenomenon called mana gate.
In this phenomenon mana gates open randomly around the globe which connect the planet to mana concentrated areas on different planets rich with monsters who are enhanced by mana causing the monster riot.
This phenomenon is universe way of keeping mana balanced everywhere. Mana gate appear and disappear randomly. But they are good source for resources.
Threat Level
S level: These are catastrophic gates that can connect to Behemoths or Leviathan. These monsters can swallow a house as a whole. Can cause continent scale disaster.
A level: These gate pose a severe, city-wide danger and require a coordinated response from multiple professional card wielders to prevent widespread infrastructure collapse.
B level: These are caused by large group of monsters, represent a serious risk, typically resulting in localized infrastructure damage that necessitates intervention by trained tactical squads.
C level: These are regional hazards cause by mid size monsters that can cause significant property damage if left unaddressed, usually handled by standard, mid-tier card weilders.
D level: These gates are classified as local nuisances, often appearing in remote or isolated areas where they can be neutralised by a small team of card holders before they escalate.
E level: The lowest tier of gate, these are minor monsters that are often dealt with by a single card weilder.