As a character, Renne has a perfectly default orbment setup that allows you to construct magic at will, while simultaneously being powerful in physical attacks, with some of her combat moves having low chances for instant death.
The only downside to her character, she's also a low HP character like Tita making her sometimes prone to being knocked out quickly. Renne can attack with her scythe and uses it to summon her giant battle robot, Pater-Mater. As part of her S-Craft 'Rennede', she can also use her scythe to call forth a group of bats.