Here is my thoughts on them so far:
1 - Dominus Aegis -- Pretty amazing for infantry support, especially tough Gravis units that are already T5 and 3W, but also quite good in supporting Dreadnought builds, since they benefit from the 5++ with their "Core" status. In terms of who to put it on, I think the most "economical" choice is to replace a Combat Shield on a Company Champion, who does not lose anything (he is only getting a 5++ natively, so no loss of the 4++ like, say, a Terminator Librarian with Stormshield would lose), is an Elites choice (so keeping all your HQ slots open) and who can buff the units around him in other ways (i.e. re-rolls to charges from a WL Trait, countercharge unit to protect shooty units, etc.)
2 - Artificer Bolt Cache -- For characters, strong on a Biker Captain with Storm Bolter (i.e. you are getting 8 shots with SIA at 24" every turn) or perhaps on a Primaris Techmarine (his Forgebolter puts out 3 x S5 AP-2 Dmg2 shots at BS2+, all of which benefit pretty well from SIA). In terms of Sergeants, I know it has been posted on this forum already, but a Centurion Sergeant with dual Heavy Bolters and a Hurricane Bolter gets a lot of mileage out of SIA, followed closely by Inceptor Sergeants with Assault Bolters and Aggressor Sergeants with Boltstorm Gauntlets.
3 - Spear of the First Vigil -- Obviously, the only option is a Watch Master, but combined with the Imperium's Sword and Paragon of their Chapter WL Traits (using Salamander +2S WL Trait), this gives you a beast in close combat with 6 x S9 AP-3 Dmg3 attacks on the charge.
4 - Banebolts of Eryxia -- So far, the best option I have found for this one is an Eliminator Sergeant -- with this upgrade, the Sergeant is hitting on 2+ with S6 AP-2 Dmg3 attacks (6 to wound still inflicts a MW, since the rest of the Mortis round rules apply). With a little luck, this model can either bring down most of a character's wounds in a single shot or even kill a 3W enemy model (like Gravis armored units) every shooting phase.
5 - Blackweave Shroud plus Adamantine Mantle (using Castellan of the Black Vault WL Trait to get a second Relic) -- Using this on a Biker Captain with Stormshield brings him up to a very durable "anvil" type character, with 6W at Toughness 6, a 2+/4++/5+++, and a 4+++ FNP against MWs.
6 - Beacon Angelis -- So many options here, but my favorite is put this on a Biker Master of Sanctity (Wise Orator WL Trait to chant on 2+s), have him chant the Litany of Hate and Canticle of Hate, turbo-boost him 20" toward the enemy's DZ, then "teleport" over a max Vanguard Veteran squad, Aggressor Squad, or Hammernator squad within 6" of him and more than 9" from the enemy. This can be done turn 1 (so basically, like using a Drop Pod, ignoring the requirement to wait until turn 2) and, with both the Litanies up, that means the teleporting unit has +2" to its charge rolls, re-roll of all to Hits in melee, and +3" to its Pile-in and Consolidation moves... pretty devastating first turn Melee Alpha Strike that often the opponent will not be expecting!
7 - Eye of Abiding -- One of the lesser known Relics, this one I think works best on Slam Captain with either MCed Power Fist (again, using the Castellan of the Black Vault WL Trait) and a Combi-Melta. Since this lets you ignore all negative to Hit, to Wound, and WS/BS modifiers, your Captain can shoot both parts of the combi-Melta at BS2+ then charge and hit a WS2+ with his Dmg3 Power Fist. Even better, on any 6s to Wound (whether with his meltagun or his PF), he ignores all Invul saves as well. While a little niche, this makes him particularly good at engaging all kinds of Aeldari, with their -1 to hit and to wound shenanigans (looking at you, Harlequins), and also quite efficient against things that rely very heavily on their Invuls to survive (again, Harlequins are a big target here, especially given how competitive they are in the current meta).
8 - Vhorkhan-Pattern Auspicator -- Another more niche choice, but potentially more useful than I think it initially appears. With a 6" aura around the bearer giving DW Core +1 to hit for their ranged attacks against "Fly" units, this can be especially effective when dealing with Eldar, Dark Eldar, Harlequins, Tau, Inceptor / Vanguard Veteran heavy Space Marines, Sisters with lots of Seraphim/Zeraphym, etc. Something I quite like about this Relic is that it works every time a unit within 6" makes a ranged attack, meaning that it is not limited to the Shooting Phase. This means that it works on units shooting at enemy arriving from Reserve with Auspex Scan, which is great for putting extra "punch" on those Deep Striking Plasma Inceptors that just landed in the back corner of your deployment zone.
9 - Tome of Ectoclades -- Saving what I think is the best for last, this Relic is so flexible, since it lets you decide mid-battle (i.e. you can activate it in any of your Command Phases) when to use it and also gives you total freedom to decide what enemy data sheet to use it against. Since any DW Core unit within 6" gets full re-rolls to Wound against any units with the selected data sheet, this means you use it to either "nuke" a lynchpin enemy unit (say, a Primarch, big squad heavy hitters, critical buffing character, etc.) or dramatically increase the damage of your army against a whole bunch of units that your make up a large component of the opposing army (i.e. say he has lots of Ork Boyz squads, or multiple Necron Warrior Phalanxes, or a whole bunch of Harlequin Starweavers, or even massed White Scars Assault Intercessors bearing down on you in a "white tide" style tactic), you can make all shooting and close combat attacks dramatically increase their damage output against these key units. One of my favorite "surprise tactics" with this is to combine it with a Pobos Librarian and a 5 Eliminator Combat Squad (from a Phobos Kill Team) that are dropped out of an Impulsor after it moves 14" -- between the 14" move, their 3" disembark, 6" move, and their 36" range, they can effectively target any character within 59", so pretty much anywhere on the board that the Impulsor can get them LOS to. The Phobos Librarian then casts Soul Sight on the Eliminators and uses the Tome of Ectoclades, giving them full re-rolls to Hit (shooting at BS3+, since they are BS2+ normally and have -1 to Hit from moving with Heavy Weapons), to Wound, and ignore cover -- against most T4 / 4++ characters, this gives a better than average chance of surgically (and unexpectedly) removing a lynchpin character from the enemy army and also can have the psychological effect of taking out someone your opponent thought was safe from your snipers.
Edited by L30n1d4s, 23 December 2020 - 01:24 AM.