Interesting. Do you have a reference for this requirement?
CR 3 is an avage encounter for a level 3 party
DMG P. 48
A monster’s Challenge Rating (CR) tells you the level of the party for which that monster is a good challenge. A monster of CR 5 is an appropriate challenge for a group of four 5th-level characters. If the characters are of higher level than the monster, they get fewer XP because the monster should be easier to defeat. Likewise, if the characters are of lower level than a monster’s Challenge Rating, the PCs get a greater award.
One page 49 we see this chart
Table 3–2: Encounter Difficulty
% of Total Encounter Description
10% Easy EL lower than party level
20% Easy if handled properly Special (see below)
50% Challenging EL equals that of party
15% Very difficult EL 1–4 higher than party level
5% Overpowering EL 5+ higher than party level
and it explains
*Easy: The PCs win handily with little threat to themselves. The Encounter Level for the encounter is lower than the party level. The group should be able to handle an almost limitless number of these encounters.
*Easy if Handled Properly: There’s a trick to this kind of encounter— a trick the PCs must discover to have a good chance of victory. Find and eliminate the evil cleric with greater invisibility first so she stops bolstering the undead, and everything else about the
encounter becomes much easier. If not handled properly, this kind of encounter becomes challenging or even very difficult.
*Challenging: Most encounters seriously threaten at least one member of the group in some way. These are challenging encounters, about equal in Encounter Level to the party level. The average adventuring group should be able to handle four challenging encounters
before they run low on spells, hit points, and other resources. If an encounter doesn’t cost the PCs some significant portion of their resources, it’s not challenging.
*Very Difficult: One PC might very well die. The Encounter Level is higher than the party level. This sort of encounter may be more dangerous than an overpowering one, because it’s not immediately obvious to the players that the PCs should flee.
*Overpowering: The PCs should run. If they don’t, they will almost certainly lose. The Encounter Level is five or more levels higher than the party level.
So as it is CR3 it should be challenging to a level 3 party..so they should be able to deal with it 3 or 4 times on avage......so if it is a CR3 they should be able to overcome the damage it does to them without a higher level NPC helping them If not it is a higher CR then the group...hince not CR3
with that I am done with the allip thing...most folks think drain is not a 3rd level ability. If you have an issue change it back. Now can we drop the allip thing for the love of the gods