Per PH- Cure and Heal type spells do not work on Undead. This includes Lay on Hands (per PH), and by extension, any Cure or Heal potion or rubber.
Taking a page from previous editions- Inflict Wounds and Harm type spells will heal undead as if they were Cure or Heal spells. Tim's Lay on Hands will act as a Inflict Wounds so he can heal himself.
This also means that Cure and Heal type spells will damage the undead as if they were Inflict or Harm type spells.
Healing Undead
Healing Undead
kyle wrote:The party then goes full retard