These CAN see invis but don't usually. And it has nothing to do with level since I ran into a blue con (my toon was 84) which did and a white con which did not.
Be forewarned!
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Sippin 115 DRU **** Firiona Vie Master Artisan (300+) * Baker * Brewer * Fletcher * Jeweler * Potter * Researcher * Smith * Tailor My crew: 115 WAR ENC CLE MAG WIZ SHD SHM Master Alchemist ROG Master Tinkerer & Poison-Maker