Well, sure you need to roleplay it if you can't use your best (possibly only) attack against minions because they'll die from it and you don't want to leave a trail of corpses behind you.
But since this is actually for an NPC, it's sooo much easier: No GM approval, no point cost, and the complication is for the players "Hey guys, your teleporting friend here just sliced a few civilians in two... I hope you have a first aid kit, and here is your Token" I might just do it ^_^
More questions: Teleport, with extended and portal... If I read portal correctly, you open a portal as a free action, need your move action to enter it, but also your standard action to concentrate on the power and keep it open... any way to make an extended portal ? Maybe with Extra Effort to get another standard action ?