Okay, so diving into Milim's battles from 'That Time I Got Reincarnated as a Slime', I feel like a lot of people get her wrong. She's not just a brute. Take her fight against Clayman's manipulated Charybdis. The strategy there was all about control and precision, not just blowing everything up. She had to neutralize a berserk, city-destroying monster without killing it, because it was really her friend. That's a crazy tactical constraint. She used 'Drago Nova' but held back, focusing the blast to break the control magic without vaporizing the core.
Later, her whole 'playing the villain' arc during Walpurgis is a masterclass in long-game strategy. She pretends to be under mind control, joins the bad guys, all to draw out the mastermind and protect her alliance with Rimuru. That takes way more cunning than people give her credit for. She's not just reacting; she's setting the board, letting enemies think they've won so she can smash their plans later. Her battle against the Empire's forces later on is just pure, unleashed spectacle, but even then, she's following Rimuru's overall war plan, showing she can be a team player despite her power.
Honestly, her most interesting strategy might be her initial 'test' of Rimuru in the cave. She throws a punch to gauge his strength and character, not to kill. It's a recruitment drive wrapped in a battle. People forget she's an ancient being; she's learned that sometimes the best move isn't to destroy, but to observe and invest.