skullcap is good to stretch psychedelics further as it potentiates any drug (its an maoi)Damiana is a very useful medicinal herb. It kills headaches, stomache aches, pretty much just minor aches and pains, is used for PMS (handy to have around if you have a girlfriend). Theyre also both good for those desperate times without weed.
Weed is also more effective than damniana at pretty much anything you would want it for.