Help with changing sprite

-- A basic monster script skeleton you can copy and modify for your own creations.
comments = {"Smells like vanilla...", "Sage is thinking about Noelle\rDeltarune.", "I don't think they know what\ris going on here."}
commands = {"Strum guitar", "Proceed", "Beg for mercy"}
randomdialogue = {"Sorry I'm all outta brain.", "Do we really have to do this.", "Have you heard of Alex G?"}

sprite = "empty" --Always PNG. Extension is added automatically.
name = "Sage"
hp = 250
atk = 10
def = 1
gold = 32
xp = 154
check = "They seem to have been forced\rinto this fight."
dialogbubble = "right" -- See documentation for what bubbles you have available.
canspare = false
cancheck = true


weirdcounter = 0

-- Happens after the slash animation but before
function HandleAttack(attackstatus)
 if attackstatus == -1 then
        -- player pressed fight but didn't press Z afterwards

else
        -- player did actually attack
       SetSprite("sagehurt")
                monstersprite.yscale = 1
if hp < 100 then
            currentdialogue = {"Not...", "Not doing so hot..."}
end
        end
end
-- This handles the commands; all-caps versions of the commands list you have above.
function HandleCustomCommand(command)
    if command == "STRUM GUITAR" then
        currentdialogue = {"Don't even try it."}
BattleDialog({"You reached for their guitar."})
    elseif command == "PROCEED" then
        if weirdcounter == 0 then
	currentdialogue = {"Girl what."}
BattleDialog({"You said 'proceed' with a horrific vocal fry."})
	elseif weirdcounter == 1 then
	currentdialogue = {"???"}
BattleDialog({"You said 'proceed' this time with more affliction."})
	elseif weirdcounter == 2 then
	currentdialogue = {"Okay.", "you're weird."}
BattleDialog({"You said 'proceed' with unbreaking eyecontact."})
	elseif weirdcounter == 3 then
	currentdialogue = {"No\nseriously.", "That's creepy. Knock it off."}
BattleDialog({"You stare directly into their eyes almost as if you could see into their soul.", "You say 'proceed'"})
else
Audio.Stop()
	currentdialogue = {"Okay this isn't funny anymore", "you're being INSANELY creepy", "I'm not going to keep doing this if...", "if you keep...", "UGHH.", "STOP MAKING THAT CREEPY FACE."}
BattleDialog({"You say 'proceed'."})
	end

	weirdcounter = weirdcounter + 1


    elseif command == "BEG FOR MERCY" then
           canspare = true
        currentdialogue = {"DAMN.", "you didn't have to make it weird."}
BattleDialog({"You got on your hands and knees and screamed how sorry you were."})
    end
end