Tego was a protective spell used by a magic practitioner to block attacks by creating a barricade. The spell summoned a nearby object to be placed directly in front of the caster, thus preventing bodily harm. However, since this spell utilized objects to act as physical barriers, it would seem unlikely that this spell could block powerful magical spells. The incantation is Latin for "conceal", "hide", "shield" or "protect".
In 2002, Giles, empowered by the Devon Coven, used this against Dark Willow. The spell was effective in summoning a training dummy that blocked knives, throwing stars and other sharp weapons telekinetically controlled by Willow.