As I stated, and maybe should clarify, usually 3, for specific, read lower, ranks of Thrash. Higher rank versions hit for 3 attacks + 1 = a total of 4 attacks. The undead don’t use Thrash, well some do, they use another attack but I cannot remember the name of it.
Also as I stated that is fairly typical of the mobs in EPL due to the fact that it was endgame content. The mobs aren’t meant to be farmed or easily killed. Which is why most people formed groups for those quests - not to mention for the pvp as well. Argent Dawn rep was highly sought after for many in Vanilla.
Hence the harder mobs being justified.