Should I level my dragons with Meat or through combat?

Both methods raise a dragon's Reign Level — the choice depends on your situation:

• Combat gives you XP on top of loot and objectives (you advance on several fronts at once). XP = enemy troops killed, and the Combat Training research boosts it by +2.5%/level in PvE.
• Meat is a direct shortcut: you gain levels without fighting, handy to catch a key dragon up fast early in a Reign.

The recommended approach: fight for your main progression (you earn XP + rewards + event objectives), and use Meat as a targeted boost on the dragon you want ready right now.

Either way, remember that this level resets every Reign: it's effort to redo each season.