So what happened last year? I ended a two-year siege, in spite of pissing off the elven traders the season immediately before, no one went hungry. A forgotten beast crept into my worst-defended zone but was eventually taken out by vigilant patrolling. A minotaur appeared and got whacked by the dwarven merchant before coming into threat range. I mountain titan flew straight down into my magmaworks, which was evacuated and deployed to just in time to take him down without a loss. Overall, the birth rate was slightly higher than the death rate, and less than half the coffins have been occupied.
At the top of this year, while I was overhauling the defenses to my Depot approach, a goblin siege arrived, found the hole in my security and went straight toward it. I decided to let them, since it drew them into a tight bottleneck that blocked their missile fire. Most of them died coming into the hole, the fighting spread out onto the mountainsides where the rest of them were mopped up. When the siege broke but the fighting continued, I realized a goblin ambush was lurking there as well. They must have been just as surprised, because they didn't live long. Again, cleaned up without a loss.
These guys really aren't elite skill. Some are close, but many are middling, and a few are mediocre. But they are well-equipped, in full steel mail and leather, all with steel edged or silver blunt weapons.