[JimMorrison]

Dunno about immortal..... It could work, but immortal free spawns might be a bit much. Now, if there were a summons that took E gems, that could Summon Allies for more mid tier units..... And those mid tier units gained free spawns..... Maybe make the larger units immortal, since they resprout from the mycellium after being damaged severely. The freespawns aren't part of the main fungal mat, so they die. But It's hard to kill off the larger myconids, so they continue gaining huge numbers of free spawns as you push them back.

And of course, there could be a few different flavors, with different roles in combat, so there would be quite some strategy in what you summoned, and how you used your national summons. But if you had some of your best summons doing Summon Allies constantly, you could have an army of mini thugs to face the incoming SCs, and they would be backed by a flowing mass of chaff that is essentially mindless, 50 Morale to really test the stamina of the enemy.