• udāra-matiḥ — of generous mentality
  Compound. Udāra — magnanimous. The narrator marks Jarāsandha's generosity at the exact moment it becomes the cause of his death. The trait is not condemned; it is honoured even as it kills him.
• kṛṣṇa-arjuna-vṛkodarān — to Kṛṣṇa, Arjuna and Bhīma
  Compound accusative. All three named together — the trio that will end him. He still believes them brāhmaṇas; the narrator already names them as themselves.
• vriyatām — let it be chosen
  Passive imperative from vṛ. 'Whatever you choose, let it be chosen.' The mood is formal, almost liturgical — like a yajamāna's invitation to ṛtviks.
• ātma-śiraḥ — my own head
  Compound accusative. The standard kṣatriya hyperbole — 'even my own head'. Spoken to Bhagavān, hyperbole becomes prophecy: in this chapter the head will indeed fall, though as part of the whole body torn apart.

• Where am I quietly reserving conditions in my generosity?
• What 'whatever you wish' could I genuinely mean today?

A king signs the contract with full theatre — 'even my head if you wish.' The audience hears bravado; the three brāhmaṇas hear permission already granted. The script has tipped from negotiation to ritual.