That island is large enough to go full Rambo First Blood, if you've seen that movie. Of course it's good to be prepared. Magelight can be used to misdirect foes, for instance.
Really, playing the sneaky summoner on the iron path difficulty, the first time the main story fight really required either console cheating or serious preparation was after the warning message "accepting this quest leads straight to finale of the story", which is quite far in the main quest chain.