Scourges with standard Shardcarbines and Razorwing Jetfighters with Disintegrator Cannons do nasty, nasty things to infantry in general. Actually the Razorwing with Dissies and a Splinter Cannon is a giant middle finger to Orks in general as they really have no answer to the missiles and Dissies mean that they're going to be having to roll boxcars to survive them. Plus that can punish any bad bubble wrapping of the characters buffing boys.
I also find Wyches very useful for tarpitting in general. If you are smart with how you charge into combat and how manipulate your Pile-ins you might only be fighting 3-4 Boys at a time from that 30-Boy horde.
Honestly Orks and Nids are a bad matchup for Pure Drukhari lists. If you are willing to look into the Craftworlds list there are several units that are
very good at killing lots of Orks quickly:
Wraithguard with D-Scythes: They do horrible things to all infantry. 5/10/15 "shots" on a Conscript or Boys blob doesn't sound like much until you realise that it's an average of 4.17/8.33/12.50 dead Boys plus the additional casualties inflicted in the Morale Phase then it applies. Depending on leadership you can end up causing a significant chunk of damage in the Morale phase, or force your opponent to burn some
CP.
Dark Reapers: The Reaper Launcher's anti infantry mode is Heavy 2 S5,
AP-2, 2 Damage. That alone is enough to terrify Ork players as not even the Painboy will save them. You are averaging 17.78 Wounds worth of damage each turn. Even with a Painboy that is going to be roughly 10 dead Boys per turn from one unit alone. Not enough? Toss in Yvraine and get a total of 40 shots in one turn. That is a total of 35.56 damage on average overall. Even with a Painboy there's not going to be much of that 30 Boy blob standing after that...
Shadow Spectres: Each one is a Jetpack infantry with 18" of movement,and a weapon designed to take on infantry of all types. They are also -1 to Hit so really like having a Hemlock or Jetbike Warlock around with them. Their gun has 2 options: one is S6,
AP -3, 1 Damage and each hit lets you roll to hit again (up to 3 times or until you miss). From a 5-Elf squad you can expect on average 7-9 hits. This is awesome for melting Nobs, Bikers and Warriors. Then there is a Heavy Flamer mode. It's basically 5 Heavy Flamers, it's
nasty. You can expect on average a third of a 30 Boy Blob to vanish each turn, and nobody is going to want to charge that unit due to taking 5d6 S5
Ap -1 Auto hits. The Exarch also forces people to roll twice for Morale and take the highest result.
Hemlock Wraithfighter: More of a support unit, especially compared to the Drukhari flyers which are arguably the best in the game right now. They have 2 Heavy D-Scythes which would be 2d3 Auto hitting S10
AP -4 shots, plus the Mindshock Pods add -1 to Leadership and the pilot has access to all Warlock spells, combined with the Shadow Spectres you can set up somepretty nice leadership bombs or use it as a mobile -1 to hit flying bunker.
Corsair Reavers and Skyreavers: They can take Shardcarbines for free! Plus they have Special and Heavy Weapon options that make tactical Marines jealous. The standout weapons are Shuriken Cannons, Splinter Cannons, Flamers and Aeldari Missile Launchers. Plus if anything gets within 8" you can use thier Brace of Pistols which is
d6 Poisoned shots that have -1AP on a 6. Plus they have grenades. Seriously a unit of 5 within 8" puts out 5-30 shots! A unit of 10 can potentially do 10-60 and a blob of 15 can do 15-90. Nobody will want to charge these guys. Reavers are best used as anti-deep strike and objective camping while Skyreavers with thier jetpacks are more mobile and are nearly as good at screening as Razorwing Flocks and Scourges.
Harlequins are also an excellent Close Combat option if you need it:
Let's take 1 Troupe Master and 5 Players with Fusion Pistols and Caresses (In this case S5
AP-2 is more valuable than S4
AP-3 due to Orks having terrible saves) in a Starweaver and charge them into a unit of Boys and Mathhammer it out:
2 Shuriken Cannons: 2.22 dead Boys
1 Fusion Pistol from the Troupe Master: 1 dead Boy
5 Fusion Pistols from the Players: 2.78 dead Boys
5 Swings from the Troupe Master: 4.32 dead Boys
20 Swings from the Players: 15.8 dead Boys
3 Swings from the Starweaver: 1.98 dead Boys
So in total that one unit is killing on average 28.1 Boys in a single charge, causing the unit to wipe in the Morale phase.