Once Shiny is at a safe distance and the spiders have lost interest, he tries to heal his severe wounds. Since he's alone and in a dangerous environment, he says his fake clerical incantation to Vecna, Master of the Spider Throne, only under his breath.
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I assume he has time to get a couple of spells in, though he keeps an eye on his surroundings as best he can and will stop if interrupted- he keeps casting until he is fully healed.
UMD: (1d20+10)[24] Heal: (1d8+1)[6]
UMD: (1d20+10)[25] Heal: (1d8+1)[3]
UMD: (1d20+10)[19] Heal: (1d8+1)[6]
UMD: (1d20+10)[21] Heal: (1d8+1)[8]
UMD: (1d20+10)[26] Heal: (1d8+1)[2]
UMD: (1d20+10)[25] Heal: (1d8+1)[7]
UMD: (1d20+10)[28] Heal: (1d8+1)[5]
Unless I am mistaken, that takes three charges in four rounds to get to full.
Once he is finished, he continues his journey, uninjured but more nervous than before.