I personally just rules lawyer back twice as hard.

• Well, technically revivify requires you to target a creature not the corpse of a creature…
• Actually detect magic doesn’t exclude itself, and the passive detection is pass/fail, so unless you’re immune to divination…
• Oh, the demi-lich got errata’d to have more hit dice, but they never “corrected” the default hp based on the special Undead Nature trait, so now it actually has %60 more hit points than the stat block would imply.
• Sure, freedom of movement lets you escape these non-magical restraints, but you have to spend 5 feet of movement to do it and your speed is currently 0.

A fair chunk That Guy’s tricks depend on a lenient or permissive DM/cherry-picking the most favorable rules & interpretations. If you don’t shadow-patch a bunch of fixes to make things work how people expect them to the game breaks down. If they want me strictly following the rules I’m happy to oblige, but I’ve never seen a powergaming munchkin who could withstand the amount of nerfing actually playing RAW causes.