Spent three hours on a stripped freehub body that should have been a ten minute job

Had a bike come in yesterday with a rear wheel that wouldn't spin freely. Figured it was just a sticky freehub, a quick clean and grease. Got the wheel off, pulled the cassette, and the freehub body wouldn't budge. The splines were totally rounded out from someone forcing it. I tried every trick, heat, penetrating oil, my biggest vise grips with a cheater bar. Nothing. Ended up having to carefully drill out the old freehub body without damaging the hub shell, which took forever. The whole thing ate up my whole afternoon. What's your go-to method for a freehub that's welded itself on like that?