"Hmmm...... What if I don't want to?" He simply asks with a rather wide grin, before seemingly fading from view.

Spoiler
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He should be 10ft away from them now, and able to cast Invisibility without any worries.

Casting invisibility.
Moving 15ft to the right.
Move Silently check: (1d20+11)[30]

OOC: Yay first combat! Hmmm.... Now how to deal with them. They'll most definitely come after him if he simply runs away.....

Choices choices...