The Atharvanic rudra gAyatrI
The Atharvanic tradition records a special rudra gAyatrI that might be used in regular japa in place of the traditional rudra sAvitrI. This mantra is:
tasmai devAya vidhmahe | mahAdevAya dhImahi | tan no rudro .anumanyatAM ||
This is known as the atharvashikha and is high mantra for those on the mAheshvara path.