Resonance

Some bosses are lazy, and don't like to move. Or they're rooted in place and can't. Either way, it would be too easy to let the ranged DPS sit back and wand the boss to death.... so the encounter has a device by which the raid suffers if it attempts this.

Raid damage is the most common punishment, and in some encounters the boss will actually knock back players - or make it unwise for them to stay close the entire time - just to add a challenge.

When a boss's adds root themselves and start emitting damage, Don't Stand in the Fire.

Examples

• Shadow Labyrinth
  • The trope namer is Ragnaros Lite, aka Murmur from Shadow Labyrinth.
• Molten Core
  • Ragnaros's Magma Blast.
• Naxxramas
  • The Four Horsemen root themselves in the corners of their room. If you have tanks there, all you have to eat is their Stacking Debuff...
• Ulduar
  • Kologarn's Petrifying Breath.