Seeing as every man and his wolf-rat has done a breakdown of their favorite faction, I'm gonna put forward one of my own. The goal is to only make claims based on experience and playtesting here, not making claims built on untested math-hammer. This blog post will cover the battle traits of Clans Pestilens, which are called "Strength in Numbers" and "Echoes of the Great Plagues".
Strength in Numbers
No two ways about it, this is a solid battle trait. on average it'll net you an extra 2 bravery, and if your monks are near a furnace (they are) that's an extra 1 bravery again. Suddenly your plague monks are bravery 8. Is that braver than a Stormcast Paladin? It sure is. This is a fantastic battle trait and I would expect to see all skaven alleigances feature this (Skryre does too already). I would play Pestilens Alleigance over Maggotkin or Chaos Grand Alliance just for this, even without Echoes of the Great Plagues. Which brings us smoothly to...
Echoes of the Great Plagues
Ain't this a treat. Given you're already spamming prayers (What even is the Rule of 1 lmao) this is just icing on an already rotten and tasty cake. On an UNMODIFIED (don't even think about it Neverplague) roll of a 6 from a Plague Priest or Furnace when praying you get to pick one of 5 uberplagues to throw at your opponent. Almost all of these feature the clauses "within 13 inches" and "nearest possible" so don't go expecting to roll a 6 and win the game, you have to work for it Plague Priest. Let's take a look at the contenders.
The Neverplague - For the rest of the game, add 1 to the prayer rolls of all PESTILENS PRIESTS in your army for the rest of the game. It's solid, non situational and best used early. The trick is to spam prayers in turn 1 with everything you have to get this. Nothing within range to debuff? Target the ground with the Pestilent Breath ability. A lucky 6 on turn one will have you praying like the pope the rest of the game. Don't be dumb however, if the enemy is nearby and you can damage them heavily with one of the other Great Plagues then TAKE THE SHOT.
The Redmaw Plague - I want to love this one, but damn is it hard to get off. The nearest enemy hero within 3 inches of it's allies but not within 3 inches of you is yours during the combat phase. I've pulled it off one or two times, but the wording on it is super limiting. Maybe this will go off once in a while and be a game changer, but it's mostly just super situational jank.
The Bubonic Blightplague - This one is probably my favorite. It's short sweet and to the point. The nearest enemy within 13 inches takes d6 mortal wounds, and if they die the nearest enemy to them takes d3, if they die, nearest enemy takes d3 ad infinitum. Don't expect the combo chain to happen, but that isn't what makes this good. D6 mortal wounds is a hell of a lovetap, never understimate it.
The Undulant Scourge - I like this one. Kind of odd and very unique, the Undulent Scourge (or as i affectionately refer to it, Pestilens Nuke) is a tasty wee plague that lets you select a MODEL in the nearest unit within 13 inches. Yes, select a model, this prayer is one of less than a handful in the game that lets YOU decide where the wound goes, not the enemy. Anyway, the assigned model takes a wound. The fun doesn't stop there however, now every model in the unit within 3 inches takes a mortal wound too. Did you just blow a hole in a mystic shielded unit of Dreadspears sitting on an objective with 17 mortal wounds? Yes, yes you did. This isn't situationally good, it's situationally insane.
The Crimsonweal Curse - Sadly GW kind of phoned it in on the last ability. The nearest unit with 13 inches takes a single mortal wound. They proceed, as well as every enemy unit within an inch of them, to take one in each of your hero phases for the rest of the game. Would be ok if the range was 3 inches, but it isn't. Use it if nothing else applies, and that's about it.
Hope this helps out if you're just getting into Pestilens or you're just here to know thy enemy. Up next will be an analysis of the Command Traits and Artifacts of Clan Pestilens.