Help the poor death lizard survive a high-level party.

[Boggartbae]

Give it Die Hard as a bonus Feat, Then the barbarian rage ability and 2 rage Powers. Give it Guarded Life and Greater Guarded Life. Then, every time it takes damage to go below 0, it instantly converts an amount of lethal damage it's taken (not just damage from the attack that dropped it) equal to 2x HD into nonlethal damage, but because it has diehard it should remain conscious (RAW this doesn't work, but ferocity effects should work through nonlethal damage too). Then on The Death Lizard's turn, the fast healing and regeneration heal an equal amount of Lethal and Non-lethal Damage, effectively doubling the healing abilities whenever it gets low on health.

Another thing to to would be to change the fast healing and regeneration to (SU) effects, so that the Fast Healer feat could apply.

Finally, ability focus on the feeble mind ability should take the wizard out of the fight on round one.

EDIT: Also change it's type to aberration. I'm pretty sure that aberration should supersede fey when your stacking templates, and the hit dice are mostly better anyway. Also, give it greater dispel magic as an SLA. or Disjunction if you're feeling mean.