The Stymphalion-E is designed as a much needed atmospheric drop-ship for missions between Sèlene and Gaia. It was developed for the needs of the epibatoi instead of the Kalshodar. The latter need the older Gryphon for its size, power, and durability. The former require more flexibility and speed, owing to their vastly different combat doctrines. As a squad of Kalshodar can overwhelm pretty much any defences in short order, the lighter epibatoi require rapid insertion and support, which the Stymphalion-E variant easily provides.

Fitted with a widened "hold" area that can safely carry 10 epibatoi and their equipment, the Stymphalion-E has been fitted with four additional AX-3 Helion engines for speed and power when needed. Its Boreas thrust vectoring engines have been improved so that it can hover and land vertically as does the standard model but with greater weight. It can drop its passengers quickly and then hover over station to provide fire support as well as quick extraction if needed. It also serves as an armoured hard point for disembarking epibatoi and has been fitted with various antipersonnel kinetic battery ports as well as grenade dispensers. The front troop ramp allows exit under the cover of all of its guns.

The Stymphalion-E has quickly seen the Gryphon relegated to heavy equipment and materiel transportation in the absence of Kalshodar passengers. Sgt. Gwydion has even adapted a few of the lumbering old beasts to fulfil the Stymphalion's original role, filling the troop hold with timed explosives to efficiently carpet bomb strongpoints and well dug-in opposition as well as heavy fortifications. As heavily armed as its predecessor, the Stymphalion-E is now twice as deadly and four times as useful.