IronAxe
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Iron, I did some quick calculations here regarding the leprechauns, and it turns out
On the first day, Sandro can easily pump up his mana level using them (ideally up to 324 units plus his initial 40, totaling 364 units); with that level, he honestly might not even need to return to the Fortress.
I did some more calculations for my Walkthrough variant and it turns out there is (though likely only theoretically) a possibility to put Sandro in the boat at the end of the sixth day. But that would be an even bigger pain than having fairies knock out nomads on the first day, which you suggested :)