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Melee Prowess: Drop sources, locations, and probabilities
Mobs Dropping Melee Prowess
Melee Prowess can be dropped by most ennemies in Warframe. You should probably consider this as your primary farm source.
Other items:
Melee Guidance - Melee Duplicate - Melee Doughty
Melee Crescendo - Melee Fortification - Melee Vortex
Melee Guidance - Melee Duplicate - Melee Doughty
Melee Crescendo - Melee Fortification - Melee Vortex