Maybe I was just lucky, IDK.. Not sure, but it seemed to me that only the Ancient Mephits summoned Young Mephits. Once I killed all the Ancient Mephits,
no more Mephits were summoned. My problem was that the mephit turns took forever. Each mephit spent a long time "plotting their move". Fight took forever.
One tip. I worked my way around to the side of the tree where there are two broken pillars (one short and one taller). You can jump on top of them but there
is only room for one person on each. BTW, I did this with only two party members. Seems the one on top of the taller pillar cannot be hit by any enemies.
My other char on the shorter pillar could be attacked (and died). I just killed everything from the tall pillar using my bow. If you do this, but your best archer on
the taller pillar.