I don't have deer problems myself, but my sister in Montana does and I've read a lot to see if I could help her. I read that castor beans (source of castor oil and the deadly poison ricin) would help but she said they ate them up. I've read that they get used to pretty much everything you can use but if you change regularly it helps for a time--guess you could rotate, say, garlic clips and Deer Off and eggs. Not an easy problem to solve; I'd think the oxalates in aroid foliage would discourage them as much as anything!