1500 vs mechanicum

Been playing a friend recently who has been working on building a mechanicum force. All was good untill he got himself an onagar which is now the bane of my army

From my experience so far have found that scourges are best fit for taking them out as they explode any vehicle that makes LOS with it.

Ive made a 1500 list and am looking for some general advice against mechanicum as well as thoughts on the list.

Succubus with glaive,
5 warriors in venom with blaster. venom with dual cannons
5 warriors in venom with blaster. venom with dual cannons

Scapal Squadren, ossifactors and dual cannons venoms

Grotesquerie
two squads of 4 in a raider with nightshields
Haemonculus with sump in one raider, succubus in the other

Ravager with 3 dark lances and nightshields.

Plans basically to zoom up the raiders with the grots in them whilethe wracks distract the back field. Warriors take the midfield/objectives. Ravager to focus and weaken whatever is best, then to be followed up by scourges finishing them off. Thinking deepstriking scourges in would be best as last game I started them on field and they got obliterated before they were any use.
The onager is by far the worst thing he has as its kitted out to kill any skimmer it sees each shooting phase.

Anyhow looking for any advice on the list and tactics to death with mechanicum

Do you know if your opponent has lots of the high toughness monstrous creatures or just lots of the infantry? If he is more the infantry/sniper type, you might want to swap the ossifactors for the liquifiers. Only toughness 3 on the snipers means you can deep strike in turn one, unload with both the liquifiers and mop up with the venom cannons.

If however he is more of the monstrous creature type, then the ossifactors are probably more useful.

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he has two squads of 10 skitari, one with snipers and other with plazma.
two stryders with twinlinked las
an onager kitted with anti skimmer guns.
a strike avenger plane
a knight errant of mine that I've been letting him use
lastly he has an Hq with 3 of the battle servitors.

Both the Onager and Knight have interceptor weapons. Destroyed my plane the turn it came on last game.

I mostly struggled with getting a AT close to the onager while the knight was in my face

Made another 1500 point list with the following

Archon with wwp, shadow field, haywire nades, Blaster

trueborn with 4 blasters in a raider with nightshield. Archon joins them

5 warriors in venom with blaster. venom with dual cannons.
5 warriors in venom with blaster. venom with dual cannons.

Scalpel Squadron, ossifactors and dual cannons venoms.

5 scourges with 4 haywire blasters each.
5 scourges with 4 haywire blasters each.

Dark Artisan

Haemonculus with wwp, Liquifier, Sindriq's Sump, Vexator Mask and agoniser.

Talos with Ichor Injector

Cronos with Spirit Probe


So this list ill try just drop my guys in up close to his and pop them. Not sure what to do with the scourges as they will be needing to deal with the knight/onager before the trueborn drop in for the kill. I'm thinking about deepstriking one squad in near the onager to take it out, but I'm not sure what to do with the second entirely. Dark artisan will drop in the backfield and wipe out one of his squads with the two flamers. Wracks will deep strike in their backfield if viable otherwise to a save location/objective. Warriors take mid and back field objectives while their venoms fire at battle servitors.

I think this list would be best as the trueborn and dark artisan can do more damage to what he fields compared to the grotesquiere. I believe I forgot to mention the scourges in the first list but they were meant to be there.