This week’s Hammer of Math takes a look at the impact of the new Hive Mind Synaptic Link abilities out of War Zone Octarius Book 1: Rising Tide.
In November Codex: Tyranids will turn four years old, enjoying the same 2017 vintage as the Craftwords Aeldari and Astra Militarum. In the time since then GW has applied a few patches here and there, notably with Blood of Baal, but Octarius Book 1 provides the first major mechanic change to Tyranids with the Synaptic Link ability. The new rules allow you to upgrade a SYNAPSE model with a Synaptic Link for between 10 to 15 points, which allows them to apply a boost to an applicable unit within Synaptic Link Range during the Command Phase. One would think that Synaptic Link range would be equal to a model’s Synapse range, but it does not. Instead the effect is a flat 12″, with the added effect that you can bridge the ability across other SYNAPSE creatures so long the distance of every link is less than or equal to 12″.
Each SYNAPSE unit can be upgraded only once, and while there is no limit to the number of upgraded units you can apply, you are only allowed to apply between 1 and 4 Synaptic Link abilities depending on the size of the battle (Combat Patrol 1, Incursion 2, Strike Force 3, Onslaught 4). Given how cheap the abilities are it might make sense to upgrade more units than you have slots to apply.
A lot of these abilities provide modifiers, so the chart below will be helpful in that regard.
Broodlord: Master of the Shadows
Broodlords provide three cover effects: Light Cover, Heavy Cover, and if the unit is not a MONSTER and the ranged attack is more than 12″ away then they also get Dense Cover. Light Cover provides +1 to saving throws against ranged attacks, Heavy Cover provides +1 to saving throws against melee attacks unless the unit charged this turn, and Dense Cover forces enemy targets to subtract 1 from hit rolls. This is beneficial across the army, as most Tyranid units do not have an invulnerable save and a 3+ armour save at best. Going from a 3+ to a 2+ is a 25% improvement in the odds of survival before AP is applied. Oddly enough only the Dense Cover effect is particularly relevant to Genestealers, who have a 5+/5++ save profile. It might be viable with Extended Carapace, effectively giving the Genestealers a 3+ save, but this comes with the cost of losing the ability to Advance and charge.
Hive Tyrant: Malicious Direction
The Hive Tyrant bonus allows a unit to increase their pile-in move by an additional 3″ (and a maximum of 6″). This is great for units that want to get more models in close contact, doubling the distance at which they can engage units. Remember that when making a pile-in move models must end closer to the closest enemy model and if they are already touching then they cannot move further. For this reason it’s a good idea to give your models some space when charging, especially if you have 6″ of movement to play with.
Maleceptor: Focal Essence
Maleceptors are cool. They look cool, they can toss around psychic powers, they provide an aura that inflicts a -1S to incoming attacks via Encephalic Diffusion, and now they can boost a unit to increase AP by 1 on unmodified wound rolls of 6 and allow damage rolls to be re-rolled. The AP bonus will generally have a minimal effect on gameplay as only 17% of the wound rolls will apply it, and only 17% of the save roll results will be impact (so the ability will only matter roughly 3% of the time). The impact of the damage re-roll is much more significant, particularly when you consider how many units have variable damage such as Hive Guard and anything with massive scything talons. In general the most advantageous time to re-roll is when the result is less than the average value (so a 1 on a 1d3, or 1-3 on a 1d6), and under those conditions the average damage is 17% higher for a 1d3 and 12% higher for a 1d6.
Neurothrope: Psychic Creep
The Neurothrope’s bonus applies to Leadership and Combat Attrition; enemy units within 6″ of the boosted unit subtract 1 from their Leadership characteristic and 1 from Combat Attrition tests. Assuming no re-rolls or other shenanigans, and assuming that the target has taken enough casualties for a Morale test to matter, the result is that the penalty will force a Combat Attrition test 17% of the time and that 17% more models will flee as a result of failed tests.
Tervigon: Weaponised Gestation
It’s a shame that the rules for the Tervigon are so terrible, because this ability is pretty awesome. Every time a model in the boosted unit makes a ranged attack, unmodified wound rolls of 1-2 can be re-rolled. Assuming you need at best a 3+ to wound this provides a flat 33% increase in the effective number of attacks. It’s particularly effective on Termagants who can also benefit from the Brood Progenitor bonus for re-rolling 1st to hit; the effect is multiplicative so the end result is a 55% increase in output. If the unit is 20 or more this is still better than the effective 36% increase in output that Termagants get when Brood Progenitor is combined with Hail of Living Ammunition.
Trygon Prime: Feed
Assuming the Trygon Prime starts the game buried it will take a couple of turns for this ability to apply (as it’s used in the Command Phase), but Feed allows you to shoot and charge after Falling Back. Not much to talk about in terms of probability, but it’s definitely a useful ability.
Tyranid Prime: Unchecked Ferocity
Tyranid Primes allow a nearby unit to allow all unmodified hit rolls of 6 to automatically wound the target. The bonus only applies in melee but it is ideal for units with massed attacks like Hormagaunts or even Rippers. Raveners in particular get a huge bonus out of this, as they have 5 attacks base (assuming only scything talons) and re-roll hit rolls of 1. The impact of the effect depends on the wound roll. At 6+ the effect increases the average number of wounds by 125%, while for 5+ the effect is 50%, 4+ is 25%, 3+ is 13%, and 2+ is 5%. This translates to an effect equal to or better than a +1 to would for wound rolls of 5+ or 6+.
Tyranid Warriors: Bioweapon Bond
Bioweapon Bond is a universally applicable +1 to hit for any attack (ranged or melee) made by the boosted unit. The impact can be seen in the chart at the beginning of this article, but in general the effect is a 25% increase for improving a 3+ and 33% for improving a 4+. I suspect this particular bonus will see a lot of attention thanks to how useful it is.
Zoanthropes: Psychic Channeling
Only useful on units that take a Psychic Test, the bonus is that the unit can roll an additional D6 and discard one of the dice. This is a pretty significant bonus as you can see in the chart below, especially when combined with re-rolls.
The bonuses provided by Synaptic Link range from mediocre (Psychic Creep) to awesome (Bioweapon Bond) to great but not good enough to justify the unit (Weaponised Gestation). I expect to see these abilities boost several of the units that are already very good (such as Hive Guard), but they could also potentially make other units such as Raveners see a bit more action. Overall it’s a good day to be in the Hive Fleet, and a bad day to be in their way.
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