  Many, if not all, post AGB stellar systems swiftly transition from a
spherical to a powerful aspherical pre-planetary nebula (pPNE) outflow phase
before waning into a PNe. The pPNe outflows require engine rotational energy
and a mechanism to extract this energy into collimated outflows. Just radiation
and rotation are insufficient but a symbiosis between rotation, differential
rotation and large scale magnetic fields remains promising. Present
observational evidence for magnetic fields in evolved stars is suggestive of
dynamically important magnetic fields, but both theory and observation are rife
with research opportunity. I discuss how magnetohydrodynamic outflows might
arise in pPNe and PNe and distinguish different between approaches that address
shaping vs. those that address both launch and shaping. Scenarios involving
dynamos in single stars, binary driven dynamos, or accretion engines cannot be
ruled out. One appealing paradigm involves accretion onto the primary post-AGB
white dwarf core from a low mass companion whose decaying accretion supply rate
owers first the pPNe and then the lower luminosity PNe. Determining
observational signatures of different MHD engines is a work in progress.
Accretion disk theory and large scale dynamos pose many of their own
fundamental challenges, some of which I discuss in a broader context.
