Description: Annoy Blue and Black phantoms by forcing them to invade a solid brick wall (that's you).
Stats: ALL 99
SL: 700+, you can get away this because there are no level ranges on phantom invasions. You won't be able to invade or co-op, but you will get some serious invasions yourself.
A rmor: Mask of the Child/Mask of the Mother
Giant's +5/Havel's (Giant's for more damage reduction, Havel's for poise)
Weapon: You have limitless options. I use:
Right hand: Balder side sword +15/Quelaag's furysword +5, Ascended pyromancy flame +5
Balder side sword has an incredible moveset. I really prefer it.
Left hand: Grass crest shield+5/Buckler+15/Havel's shield (for being really annoying), Tin banishment catalyst
Rings: Ring of fog, dark wood grain ring
Spells: All a matter of preference. I don't use spells too often honestly, aside from crystal magic weapon for a crazy damage boost. Use power within on an unupgraded pyromancy glove to reduce the health degen. Use TWOP if you really want to get cheesy. All in all, spells just aren't that useful for farming blue phantoms because you will run out of uses pretty quickly while you're stranded in no mans land against 3 phantoms.
Battle strategy: You don't need one. You're level 700+. You could get invaded by level 30s, think about that for a moment. Mash R1 in the right direction, you will win 90% of your fights. Also spam Estus flasks.