Hello Mukai,
yes that can you make, its hard scripting and many work, hehehehehe
Show in your snow event combat system where you can find an example of this, you must HIDE youre NPC and use equal Intervals random^^
Big sry for my bad english :-P
[@Event_Start]
#ACT
loadValue P1 "Flag_Def\Event\SnowBattle\Flag.txt" [event_main] [start]
#IF
Equal P1 0
#ACT
SendCmd "snow, 39, 29, 3" ;NPC Hide
SendCmd "snow, 22, 29, 3" ;NPC Hide
ResetMapAttr "snow"
Monclear snow
Mapting snow 0 446 380 ;NPC spawn
SetAreaAttr "snow, 28, 29, 50" "NoRevival"
ChangeMapAttr "snow" "NoSpell"
ChangeMapAttr "snow" "NOUNIQUEITEM"