Built-in autosave feature (for the TE version).

The most balanced approach would be to have Mass Slow and Mass Haste as separate spells at level 4, similar to how they were in Heroes II. Mass Slow is arguably the most powerful spell among low-level spells. Therefore, it makes sense that it was nerfed in the Trial of Elements – making it harder to obtain by removing it from the starting spells of heroes and moving it to the second tier. This balanced the situation; now, in the Trial of Elements, it's not used as often, and is on par with other mass spells. Based on my personal experience, I use Mass Haste, Mass Shield, Mass Stone, and Mass Bless more often than Mass Slow. If there's a reason to take Fire for the future, Mass Cure would be added to this list as well (it's a significantly more useful spell than Mass Slow in that context). In Shades of Darkness, the presence or absence of Mass Slow is one of the central factors in evaluating the success of a build/development.