(Apologies if people already knew this, but at least my own guide and the wikis are wrong on this)
I was just trying to square some oddities I found with some effects while doing a guide update, and pretty much every major source has been wrong about the spiritshift boar DoT since the beginning. I think it started with MaxQuest's aggregated spiritshift info from the backer beta (not his fault, it was speculation based on some shortly observed data; it may have even been accurate then but it was changed and no one bothered to look closely again). Most everyone (including myself) repeats or understands that the boar spiritshift damage over time is 4 raw damage per tick, and that the tooltip is buggy and shows 0 instead.
This is wrong. The reason why the tooltip appears to be 0 is because it actually uses a rarely seen effect, where the base effect is just used for its duration and the "real" effect is triggered by damage done ("ApplyStatusEffectToEnemyByDamageDealt"). It makes sense why OBS wouldn't/couldn't fix this tooltip, because it's conditional on damage done, so it's a little more complicated than plugging in the real number (which many people thought was 4).
The boar DoT is actually 10% of actual damage dealt per tick, for 6s (adjusted for intellect). It stacks, too.
On the one hand, this means the boar DoT is much much worse for dealing with penetration/immunity issues, because it won't help you (as the original understanding of the boar dot was) in fights where you're not doing much damage with your claws.
On the other hand, this means the boar DoT is *extremely* good as an additional damage bonus in normal fights. At base intellect, because it stacks you essentially get a 30% raw lash (over time; 10% lash on initial application, plus two more ticks). Every point of intellect above 10 effectively adds 1.5% to this lash (over time). Because it's based on damage done, it should be inclusive of any wildstrike lashes, making it multiplicative of a multiplicative effect. So as an example, a level 20 spiritshift boar with modest 15 strength and modest 15 intellect and greater wildstrike will do 13-20 +75% base damage, plus a +25% multiplicative elemental lash, plus a further 37.5% raw DoT lash over 7.5s.