To be honest, at 1850 I'm not sure I'd take the Maru Skara. To be effective you need to invest a fair bit in the Hidden Blade and I think a good rule of thumb is that your shouldn't have more than 25% invested in your hidden blade (about 460 points for 1850, 625 for 2500). So constructing an effective Hidden Blade and Open Blade at 1850 points is quite limiting and especially with the point sink of a Champion it isn't always worth it. However, if I had to I'd probably play a list like this:
Delegatus: phoenix spear; boarding shield; artificer armour; The Maru Skara 115
• 3 Space Marine Chosen: 3× power sword; 3× power axe; 3× combat shield; Legion Standard Bearer (power axe; power sword; combat shield) 220
Champion: phoenix spear; boarding shield; artificer armour 125
15 Tactical Space Marines: additional chainsword; nuncio-vox; Legion Vexilla; Tactical Sergeant (phoenix spear; artificer armour; melta bombs) 280
15 Tactical Space Marines: additional chainsword; nuncio-vox; Legion Vexilla; Tactical Sergeant (phoenix spear; artificer armour; melta bombs) 280
2 Apothecaries: 2× augury scanner; 2× artificer armour 120
Contemptor Mortis Dreadnought: two kheres pattern assault cannon 180
Contemptor Mortis Dreadnought: two kheres pattern assault cannon 180
Anvillus Pattern Dreadclaw Drop Pod 100
Vindicator: laser destroyer array; combi-bolter; power capacitor 135
Whirlwind Scorpius 115
1,850 points
Still has most of the elements of the 2500 point list, but against AV 14 all I've got it the Vindicator and hopes of Glances. Still, if everything goes right, I can execute pretty much the same plan as before, but on a smaller scale.
Delegatus: phoenix spear; boarding shield; artificer armour; The Maru Skara 115
• 3 Space Marine Chosen: 3× power sword; 3× power axe; 3× combat shield; Legion Standard Bearer (power axe; power sword; combat shield) 220
Champion: phoenix spear; boarding shield; artificer armour 125
15 Tactical Space Marines: additional chainsword; nuncio-vox; Legion Vexilla; Tactical Sergeant (phoenix spear; artificer armour; melta bombs) 280
15 Tactical Space Marines: additional chainsword; nuncio-vox; Legion Vexilla; Tactical Sergeant (phoenix spear; artificer armour; melta bombs) 280
2 Apothecaries: 2× augury scanner; 2× artificer armour 120
Contemptor Mortis Dreadnought: two kheres pattern assault cannon 180
Contemptor Mortis Dreadnought: two kheres pattern assault cannon 180
Anvillus Pattern Dreadclaw Drop Pod 100
Vindicator: laser destroyer array; combi-bolter; power capacitor 135
Whirlwind Scorpius 115
1,850 points
Still has most of the elements of the 2500 point list, but against AV 14 all I've got it the Vindicator and hopes of Glances. Still, if everything goes right, I can execute pretty much the same plan as before, but on a smaller scale.