Yep, quite easily.
If you just want to use the base root templates:
INIT:
TriggerRegisterForPlayers(TRIGGER_SpawnTrig);
KB:
IF
CharacterEnteredTrigger(_Player,TRIGGER_SpawnTrig)
AND
_Player.DB_IsPlayer() //Don't need this most likely but I usually include it as a habit.
THEN
TriggerUnregisterForPlayers(TRIGGER_SpawnTrig);
CharacterCreateAtTrigger(TRIGGER_Spawn1, "ROOT TEMPLATE GUID HERE",1);
You could also pre-create the characters so you can set scripts and equip them properly and just use:
CharacterAppearAtTrigger(CHARACTER Character, TRIGGER Target, INT PlaySpawn)
Though if you did that there would be an upper limit of characters based on how many you pre-created. But like I said it would open up the ability to add equipment, set their level, give them special arrows and such. That's what I would do for a normal mod but if you just made one where you wanted to smash some enemies for fun it's less necessary.
Also you could get really fancy by randomizing it using databases. Same thing for waves.
If you want to see a concept of a spawning enemies mod check out Spuds Crud-tacular arena on the workshop. It's mostly a proof of concept thing and the author abandoned it, but it kinda shows what you can do.
Actually come to think of it, there's a really nice example in my mod A Necromancer's Crusade. The last boss fight has 3 waves of enemies that spawn. You should check it out :P
I could post the script of it for you if you want as an example.
