εἰ δ᾽ ἄρα τις καὶ μοῦνος ἰὼν ξύμβληται ὁδίτης,
οὔ τι κατακρύπτουσιν, ἐπεί σφισιν ἐγγύθεν εἰμέν,
ὥς περ Κύκλωπές τε καὶ ἄγρια φῦλα Γιγάντων.
Is ξύμβληται = ξυμβάλληται? It would be sense the subjunctive in this construction, but I can't explain the change in the stem. Is this a syncope? I thought that this kind of transformation applied only for other systems, I don't recall having seen any case like that in the present system, ...