Crystal Tower/1.03

Fey
With a high build time and very low stats both offensively and defensively, one would assume that the Fey's towers (which are referred to as Crystal Towers) wouldn't be worth building, especially considering how quickly they can be knocked down by anything even remotely decent at damaging buildings. But what they lack in raw stats, they make up for in utility.

Firstly, they offer +3 points to the Fey's army limit, instead of the usual +2. This allows the Fey's population to expand quite effectively even when being built for defensive support. Secondly, each enemy that falls to the tower's attack will be turned into crystal for the fey to use, changing hordes of failed attackers (and even harmless animals) into potentially new Fey troops. However, with such a weak attack, they require support to take advantage of this ability and even micromanaging to target the weaken enemy units.

But it's the support they receive by garrisoning them with Leprechauns that makes them truly effective and work hand in hand with each other. With garrisoned Leprechauns, the Crystal Towers receive a damage buff that makes their attacks threatening to all but the most bulkiest of units - and even then, with a magic typed they can strike though those that rely on armor to be bulky (such as Dwarves), making a mockery of their researches. And in turn, the Crystal Towers offer protection to the otherwise fragile Leprechauns, allowing them to sit in shelter without fear of being prioritized by enemy attackers who would aim to put an end to their gold-generating shenanigans.

But of course, the towers are fragile and can be overwhelmed easily, especially by high HP units that don't rely on armor to be tough (such as Dragons and Minotaur Kings), so support from units like Pegasi are advised.