I just returned a few months ago after a "7 year hiatus", and would like to know the best armor and mod setup for a sampire for doom.
A fair bit is dependent on what build (variation of the sampire)/weapon(s) you intend to use, as you will need to factor in how much SSI/Stam and possibly Dex you can get, and where. In general I'd say you need at least 40 Stam Increase on suit. Typical suit mods would be 70/95/70/70/70 for human, +5 energy for elf, +5 all if you're planning to refine your armour and lower your DCI. Then 100 DI, 45 HCI, 20-45 DCI depending on refining, 40-55 LMC depending on whether you go for that or Stam protection (check UOguide on LMC to understand this), MR is largely optional on a sampire though some carry an extra suit for when they've just been res'd. Eaters are optional. I personally always like to have +25 Str and HP so I can go 150 Str/HP and then pour any remaining into Int/Mana. Casting dependent on build but generally unnecessary.
I'd take a bit of time to figure out what new gear can get which mod you need on as that's changed a lot.