Overnight leader Michl of Austria downed birdies on the final two holes to card a three-under 69 and help peg back Luna, who had looked set to hold a slight advantage going into the final day before bogeying the 17th.
That was the only blemish for the Italian as she also collected six birdies - including one on the last - in carding a five-under 67.
Those two players are a shot clear of Finland's Kaisa Ruuttila, who had a mixed round of 68 that included an eagle, five birdies, a bogey and double-bogey seven on the par-five 10th.
France's Cassandra Kirkland, who led after the opening round but slipped down to joint seventh following a nightmare 74 yesterday, climbed back up to fourth after shooting a 68, which included an eagle on the par-five 18th.
Ursula Wikstrom of Finland, who was second at the start of the day, had a miserable time after shooting a three-over par 75 - the only player in the top 25 at the end of the third day not to have an under-par round - to drop seven shots behind Michl and Luna.
In fifth spot are Italian Giulia Sergas and Felicity Johnson of England, who are both three shots off the lead after carding 69s today.
There are four players tied at eight under, including French amateur Perrine Delacour, England's Florentyna Parker, Becky Morgan of Wales and Minea Blomqvist of Finland.
Solheim Cup winner Laura Davies of England is in a four-woman group at seven under after recovering from a double-bogey six on the first to finish with a two-under par 70.