1 Jun 2011
If damage dealt to Phyrexian Hydra can’t be prevented (due to Leyline of Punishment, for example), it will be dealt as normal and won’t cause Phyrexian Hydra to put -1/-1 counters on itself.
1 Jun 2011
If multiple damage prevention effects, including Phyrexian Hydra’s, are attempting to prevent damage that would be dealt to Phyrexian Hydra, its controller chooses which to apply.