Dragon Slayer (3.5e Feat)
From D&D Wiki
Dragon's Nightmare [General]
You've had enough experience fighting dragons to gain an advantage against them.
Prerequisite: Intelligence 13+, must have been in a party that has defeated a dragon
Benefit: You gain +2 on both attack rolls and damage against dragons of that size. In addition, you gain a +2 bonus on all your saves against a dragon's breath weapon.