Total War Warhammer/Tactics/Skaven

Why play Skaven

Because you are a backstabbing bastard that cares little about the lives of your very numerous subjects
You like bringing down classic high fantasy tropes with the power of raw industrial might, like Saruman
DOOMWHEELS
Even your most basic Skaven is by all standards batshit insane and CAs Voice Acting is spot on
You are an opportunist that takes advantage of other factions being distracted and like making plots
Skaven are entirely unique to Warhammer, in no other setting there is something quite like them
IKIT CLAW HAS FUCKING NUKES

Numbers: Even at the highest tiers, you will outnumber your enemy easily. Even higher tier infantry units outnumber every enemy unit and you have the units with the highest base model count in the game.
Firepower: Your ranged units are easily unsurpassed by any other faction, this goes for your missle infantry as well as your artillery. Skaven have the strongest ranged roster in the entire game, and don't necessarily need a lot of micro to make the most out of them.
Ambushes: Your normal movement stance on the campaign map lets you ambush enemy armies on the attack.
Cost: Everything you have is extremely cost-efficient and your melee infantry in particular is dirt cheap.
Under-Empire: You can establish hidden bases all over the world, siphoning other factions income into your pockets as well do some really crazy shit with this mechanic.

DLC is mandatory: The big issue. The "The Prophet and the Warlock" DLC is absolutely mandatory to make your faction work on the battlefield; your roster will lack essential units like Ratling Guns and Warplock Jezzails without it.
Mediocre Economy: Your economy is not the best. While many of your baseline troops are dirt cheap, your crazy weapons are not and your economy needs some time to get going, but even then, you will be overshadowed in terms of money by most other factions in your general vicinity. Special attention needs to go to your food economy, which is easily one of the biggest pitfalls an unexperienced Skaven player can fall into.
Hard to play: You need at least a basic grip at how the game works to play Skaven, they punish mistakes heavily. Your troops may be numerous and dirt cheap, but have little staying power and will rout at the first glance of danger.
Very hard start: Your starting positions (aside from Ikit Claw) put you in opposition of factions that have a lot of tools to counter your strengths. Start to fear Lizardmen, as both Queek and Skrolk have to deal with them very early on.

Verminous Valor: The Leadership of Skaven Units depends on many Skaven are left, and will regenerate faster if the unit has more models left.
Skitterleap: Skaven units get a speed bonus when they rout. Interesting ability, because it stops enemies from chasing your fodder.

To be continued