Internal Sandhi

Example:

• karo + si ⇒ karoṣi
• gaccha + si ⇒ gacchasi (remains in front because of "a")
• deve + su ⇒ deveṣu
• bhavat + su ⇒ bhavatsu (remains in front because of "t")

N Rule

When ṣa, ra, ṛ, or ṝ precedes n, n turns into ṇ which gutturals, labials and "y" potentially in between.

Examples:

• rāma + ena ⇒ rāmeṇa
• rat + ena ⇒ ratena (remains insertion because of dental "t")
• kārya + ena ⇒ kāryeṇa
• viṣaya + ānām ⇒ viṣayāṇām
• bheṣaja + ānām ⇒ bheṣajānām (remains insertion because of palatal "j")