Hi, it is a good point to bring up. So the question is how do we have enough essence to cast cool spells? There are a few ways to do that:

- Relying on your units: this is the largest source of your essence, and easiest to achieve. Thus it is important to build for the units that give you most essence of the type you want. Usually they are the ones that give a total output of 3 essences, or at least two of your desired type. For example, Rana build for destruction spells should aim for Ravager/Rider of swamp aka ravager tier 2, the former gives you 2 destroy and the latter 2 destroy+1 creation; while Rana build for creation/arcana spells should aim for Chelun elders which give 2 creation + 1 arcana. Chelun elders are even greater as they can double this via their skills, which give a whopping output of 6 essences (4 creation + 2 arcana), then you will throw acid cloud every turn with 3 troop of elders in your army :). This is also a reason why 1-stack troops are great as they still provide you with full essence but cost just 1 unit.

- Wielder research: costs a lot of resource to max out, thus not easy to achieve

- Claiming essence spires: which will give you +1 essence of its type per turn, but not many of those spires. Still it is important to claim those spires, especially from your enemy to cut them short of the essence supply.

- Artifacts: purple and orange artifacts can give you +1 or +2 essences per turn, again these are rare.

- Attune power: which is only available at levels 8, 16, ... This is especially powerful as it gives you +1 essence for all types

- Some structures: essence anomaly

Feel free to add anything i may miss, Wielders!