Spells are Magic abilities the player can use against some mana points (MP) those spell can have various effects and can evolve when the player level up. You can learn a spell by levelling up, or buying them against some exp from NPCs.
Spell possesses three stats :
Area of Effect(AoE for short)
strength who's the amount of damage(for offensive spells), healing(for healing spells), or the duration(for buff/debuff spells).
Tiers represent a spell strength, a spell can tier up by leveling up or by buying the upgrade from an NPC. The tiers are the following :
+ spells : stronger version that cost more mana
- spells : weaker version that cost less mana
eco spells : stronger version that cost the same as the base spell
tempest spells : weaker version that can hit multiple time a target
Mega spells : version that can hit multiple time a target but cost a more mana
Giga spells : stronger version that can hit multiple time a target but cost a lot of mana
Ultra spells : version that have a bigger AoE and hit multiple time a target but cost a lot of mana
armageddon spell : stronger version that have a bigger AoE hit multiple time a target but cost a big quantity of mana (the tier of this spell is indicated by the name ending by -gedon. Ex : firegedon)
Note : some spell can't tier up or only partially can.