you can FD out of spellcasts (it ends them immediately)
You can outrange the lock (he cant chase you down and has no snares unless he’s heavy Aff, and its a very bad 30% snare)
You can make sure you have a fast-attacking pet to make sure that Fear and Immolate have long cast times, and you have a much higher chance of causing pushback/time loss on Drains.
You can Viper Sting the lock (itll force him to lifetap for Mana).
But if the lock is some variant of the 20/31/0 Soul Link PvP build…
run. Just run. Leave. He cant chase you down, is your only salvation. If you insist on trying to stick around and “score that kill”, youll get killed, every single time. He’s got about 15k effective HP BEFORE you take drains into account.
His damage output is kinda low (doesn’t have a lot of the talents that buff DoTs, does not have the talents that reduce cast time on nukes) but hell just whittle you down until you’re dead.
You cant kill him alone.
But he cant kill you, either, unless you let him.
As to the situation described… something is way off. DoTs do NOT hit that hard without a CRAPLOAD of +spell damage (i mean 400+) to kill you in only 15-20 seconds. A full row of DoTs, even in heavy affliction (So, Agony, Corruption, Siphon Life, and Immolate) with ~200 spellpower will do roughly 4000 damage… over almost 30 seconds, not 15.
DoTs cant crit, and Haste is both A) not a thing in Classic and B) didn’t speed up DoT ticks till like… Cata?
If he blew you out in 15 seconds, it wasn’t the DoTs that did it. He hit you with something else. A lucky Nightfall Proc might account for some of it, but DoTs alone did not kill you in 15 seconds.