[Snowbody]

And Alessa: (1d20+1)[2]

Grouped initiative as before, when the group comes up anyone in the group can post, a limited amount of retconning is possible if it makes the battle flow better. So here's how the initiative order stacks up:

Enemy Group 1: (Minions and one other creature type)
Hero Group 1 (Mertes, Zimelda, Crabb, Arjhan, Goyle)
Enemy group 2 (3 creature types)
Hero Group 2 (Rat, Alessa)

You're not in combat until you detect an enemy or become aware that an enemy detected you (this has only happened to Mertes). If the detection is not simultaneous, the less perceptive/stealthy combatant(s) is(are) Surprised for the duration of a mini surprise round.

This happened to Mertes (his Perception check was not high enough to spot the hidden kobold minion). The kobold used its surprise action to throw a javelin and hit Mertes. Since the minion won initiative over Mertes, it now gets a regular round, which I'll post later.

You're waiting 15-20 seconds (aka 3 rounds) for Mertes to do his thing, and then Alessa is charging in, am I right?