The opening of the Cicatrix Maledictum had a striking effect on the Emperor's Blades, a relatively young chapter based in the Eastern Fringe. Much of the Blades' strength was lost staving off the predations of the alien, mutant and heretic on their recruiting worlds. These losses looked certain to see the chapter consigned to a long, slow destruction as they lost more and more battle brothers. The surviving companies placed a high priority on the recovery of equipment following engagements, and line squads came to draw ever more specialist equipment from the chapter armoury as their veteran status became more established. The most dominant squad organisation came to be that known as the "Phalanx Guard" units - so called because of the storm shields they carried and their propensity for attracting most tenacious members of the chapter. These squads came to exemplify the character of the chapter as a whole, and their actions strengthened the rumours that the chapter were among the sons of Dorn.
Then, the Indomitus Crusade came.
Guilliman's reinforcements were timely indeed, filling the gaps that the chapter's veterans could not plug themselves. The original Blades focused ever more on the creation of Phalanx Guard squads whilst their Primaris brethren filled the role of line units.
I recently posted regarding Company Veterans post-CA, and I think I may have hit on how I'd like to run mine. I'm currently building the 2 "Phalanx Guard" units along with the Repulsor.
The basic idea here is to divide the army into 2 elements - an armoured force with the veterans, smash captain, lieutenant, hellblasters, ancient and apothecary in the Repulsor and Razorbacks to take a flank, rush an objective and/or hit high value enemy targets - an "In your face" hammer, so to speak, with the intent of doing damage and holding the enemy's attention for as long as possible.
The devastators and intercessors, meanwhile, will be detailed with holding home objectives with support from the two Primaris characters.
I do, however, worry about hordes.
There may be some mitigation to be found in chapter tactics, however, and I'm not yet sure where to go with this force/chapter. From 5th to 7th, they played as Imperial or Crimson Fists, usually in a "Steel Rain". 8th, of course, has changed that.