Rishi: VS healing sequence tradition (not explicitly named in the mantra).
Devata: Oṣadhayaḥ; secondarily the empowered Bhiṣak (healing function).
Chandas: Tr̥ṣṭubh-like movement (to be verified by syllable count; the diction is RV-like).
Samhita Patha (Devanagari)यत्रौ॑षधीः स॒मग्म॑त॒ राजा॑न॒: समि॑ताविव । विप्र॒: स उ॑च्यते भि॒षग्र॑क्षो॒हामी॑व॒चात॑नः
Transliterationyátr o̍ṣadhī́ḥ samágmata rā́jānaḥ sámitāv iva | vípraḥ sá ucyate bhiṣág rákṣo-hā́mīva-cā́tanaḥ
Translationณ ที่ซึ่งเหล่าโอสถสมุนไพรได้มาประชุมพร้อมกัน ดุจบรรดากษัตริย์ในสภาประชุม; ผู้นั้นย่อมถูกขานนามว่า “ผู้มีญาณดลใจ”, แพทย์, ผู้สังหารภูตผี, ผู้ขจัดโรคภัย.
Padapatha (Word Analysis)यत्र । ओषधीः । सम्-अग्मत । राजानः । समितौ-इव । विप्रः । सः । उच्यते । भिषक् । रक्षो-हा । अमीव-चातनः ।
Word by Wordऔषधीःherbs, medicinal plants समितौin an assembly, in a gathering विप्रःsage, inspired priest रक्षःdemon, harmful spirit 
Entities MentionedO
Oṣadhayaḥ (Medicinal Herbs)B
Bhiṣak (the empowered Physician/Inspired one)R
Rakṣas / hostile beings (as adversaries)Ā
Āmīva (disease, affliction) Viniyoga (Ritual Application)