This is less Epic and more Amusingly Horrible, but I had an experience with a Brush Titan, Sanad, a great horned serpent with a stinging tail - for those of you keeping track at home, that's three body parts (fangs, horn, stinger) that were capable of delivering a blister-inducing poison.
My fort was still in its early days - Sanad was the first non-goblin enemy the site had faced since embark. Most of the population lived in small, open bedrooms near the manually-irrigated underground farms. Those areas of the fort were not yet building-destroyer-proofed, so once the Brush Titan smashed his way in, all hell broke loose. His first move was to break the floodgates that controlled the irrigation system - the sizable cistern then gushed out, knocking several farmers unconscious and filling the upper levels of the fort with a few feet of stagnant water.
The (inept) Fortress Militia was quickly mobilized, only for Sanad to bite off the commander's arms, spitting the left one out at a high enough velocity to cave in the second-in-command's skull. At this point, poisoned dwarf blood was rapidly contaminating the groundwater, but thankfully only ingestion activated the syndrome, so the surviving farmers were safe. Sanad retreated into the cistern as I sealed off the upper fortress and began re-arming the remaining hammerdwarves.
...until, of course, Sanad smashed the other set of floodgates, letting the nearby river flood the fort. This, in turn, allowed the blood-contaminated water to seep into the well, which was the only drinking source the sealed-in dwarves had. Most died pretty quickly from suffocation(?), but a few survivors already drank before the farms were walled off remained. The next in-game month or so was devoted to watching the incredibly macabre game of hide-and-seek they were playing with Sanad as they waded through the floodwaters soaked with the gore of their fallen comrades.
Then they died, and Sanad killed everyone else. I reclaimed with seven Marksdwarves and shot Sanad in the face. Go team dwarf.