Excuse me WHAT?
(I started in 5th edition)
Does 5e still have attribute damage?
it was relatively rare in 3e, precisely because how deadly it got if you put effort into optimizing for it, but there were certain special attacks and powers that dealt damage directly to main stats rather than HP.
STR damage, DEX damage, CON damage, etc. Most poisons were expressed in this format in the old 3e stuff.
The Dire Weasel, which is basically a meaner giant version of a weasel, has an ability that let's it latch on with a successful bite attack and start draining CON.
Normally the Con damage is actually on the low side, so no biggie, and
Dire animals, while impressive at low levels, are not high end combatants.
The Dire Weaselstorm has several other ingredients:
1) The Summon Monster line of spells happen to include the dire weasel as a summon option, at a certain level.
2) You can summon multiple monsters at a time by picking a lower tier monster than the level of Summon Monster you are casting. Eg, Summon Monster V can summon 1 monster from the (5) list, 1d3 from the (4) list or 1d4+1 from the (3) list.
3) The Alienist prestige class adds the Psuedonatural template to any creature you summon with a Summon Monster spell.
4) the Psuedonatural template gives a creature the ability to cast Truestrike once per day
5) Truestrike is normally a loser in the action economy past lower levels, but it does add +20 to your hit roll, which makes a creature that is normally outmatched able to at least land one blow with high confidence.
Add it all together and you can, as long as you have the spell slots, summon 1d4+1 Dire Weasels per round, each of which can
Truestrike and have a very good chance of latching on to drain CON.
Enemies with AoE effects can probably fix this, but if you're fighting a Bruiser boss that focuses on slow but brutally hard melee hits... He's SOL.