help with mvp sand script please

[ewerer]

Good morning everyone, I come to ask for your help because the truth is very new to the script, what I want is if you can help me create an event that invokes mvps per round, for example 40 rounds but in 4 phases, by killing the mvp of Round 1 to 10, an NPC and a prize come out, as they pass the 11-20 round, the NPC and double the prize come out and so on until the final round and give the jackpot to those who managed to pass the 40 rounds. of mvps, I don't know if I understood, if you could help me, I would really appreciate it n.n

reference video : 

 

[Emistry]

try

-	script	Sample	-1,{
	OnInit:
		.map$ = "guild_vs1";
		.max_round = 40;
		end;
		
	OnClock0000:
		if (.status) end;
		.round = 0;
		.status = 1;
	OnSummon:
		sleep 3000;
		.round++;
		if (.round <= .max_round) {
			mapannounce .map$, "ROUND - "+.round+"/"+.max_round+"!", bc_map;
			sleep 5000;
			monster .map$,50,50,"--ja--",-3,1,strnpcinfo(3)+"::OnReward";
		}
		else {
			.status = 0;
			.round = 0;
			killmonsterall .map$;
		}
		end;

	OnReward:
		donpcevent strnpcinfo(3)+"::OnSummon";
		addrid(1, 0, 5, .map$);
		
		// Prize + Amount
		if (.round <= 10) .@amount = 1;
		else if (.round <= 20) .@amount = 2;
		else if (.round <= 30) .@amount = 3;
		else .@amount = 4;
		getitem 501, .@amount;
		getitem 502, .@amount;
		getitem 503, .@amount;
		end;
}