Evolution is a new mechanic in Defense Witches which allows you to power up ("Evolve") a witch for a short period of time. The strength of witches and duration of the evolved phase is determined by an out-of-game "level up" process.
During a stage, players can level up witches by spending orbs. Junior witches cost one orb to power up by default, and senior witches cost two. At level 1, the power up will increase the witch's Speed by 100% for 30 seconds.
While evolved, witches will sometimes cause enemies to drop treasure boxes, which contain experience points. The amount contained in each treasure box is random, but wooden boxes range from 5 to 50 experience points, and metal boxes range from 40 to 200 experience points. Clearing a stage for the first time gives the player 800 experience, which is the fastest way to gain experience early on.
Out of battle, players can use experience points to increase the duration and effects of evolution. Most wiches follow this progression:
- Lv03 - Evolution duration increases to 60 seconds.
- Lv07 - The maximum number of orbs a player can have is increased by 1.
- Lv11 - Evolution duration increases to 90 seconds.
- Lv15 - "Evolution II" mastered, which increases Attack by 80% on top of the Speed boost. Evo II costs more orbs than Evo I, and the player can choose between Evo I and Evo II when selecting the orb option. For junior witches, the cost for Evo II is two orbs. Also, Evo II changes the witch's appearance.
- Lv19 - Treasure boxes drop 50% more often when this witch defeats enemies in evovled form.
- Lv23 - Evolution duration increases to 120 seconds.
- Lv26 - The maximum number of orbs a player can have is increased by 1.
- Lv30 - "Evolution III" mastered, further increasing the parameters raised during evolution. Evo III costs more orbs than Evo II, and the player can choose between Evo I, II and III when selecting the orb option. For junior witches, the cost for Evo III is three orbs.
Support witches such as Luna and Sarah follow a different pattern, focused on providing the player more orbs. Information suggests that the bonuses for support witches could change in a later update.
- Lv05 - The maximum number of orbs a player can have is increased by 1.
- Lv12 - The maximum number of orbs a player can have is increased by 1.
- Lv19 - The maximum number of orbs a player can have is increased by 2.
- Lv26 - The maximum number of orbs a player can have is increased by 2.
Junior witches cost 200 Exp/Lv to level up (e.g. 200 Exp for Lv01 > Lv02, 1000 Exp for Lv05 > Lv06) and senior and support witches cost 300 Exp/Lv.
Because the Evolution mechanic is fairly new, few strategies have been created. However, a few things are readily apparent.
As orbs take a long time to regenerate, increasing the maximum number of orbs players can hold is important. The smartest and most cost-efficient way to do this is to raise junior witches to Lv07.
Raising any junior or senior witch to Lv03 is always cost effective, as it doubles the duration of evolution for a very low cost. While players might not rely on witches like Bianca or Lillian often, being able to double their speed during the final wave after they are properly set up can easily make the difference between a perfect or silver medal.
Raising the support witches to any level is generally a poor investment, but watch out for changes to their mechanics in later versions.
The best way to collect treasure is to focus your offense around one powerful witch who will be able to defeat a lot of enemies, since treasure only spawns when an evolved witch defeats enemies herself. You won't get anything if other witches take out the enemies before your evolved witch can get to them! Place a gold star Daisy, Nicola, or Cecilia in prime position with several support units (Chloe, Nicola, Sarah) around them, then evolve your witch during one of the later phases. Remember that HP lost doesn't effect treasure boxes, so your setup when farming for exp will likely be different than if you were going for a perfect or SP medal.