In Warhammer lore, Grungni is the patron god of the dwarves, who forged not just the first runes but also the first armor and weapons. The Path of Grungni is the Rune Priest mastery path focuses on powerful effects on single targets, both offensively and defensively.
In Warhammer Online, some class abilities are core abilities that progress with every career rank a character achieves. Any Rune Priest can purchase these abilities as he levels. Other abilities are available to all Rune Priests but are associated with a mastery path; once you pass level 10, those abilities will only advance at half the rate of the character's advancement. In other words, if you have such an ability, it will be at level 25 when you hit rank 40. But for every point you put into the associated mastery path, you will gain an additional spell level. So if you are rank 20, your Rune of Serenity will be at level 15, but if you put 5 points into the Path of Grimnir, that same spell will be at level 20. Still more abilities are only available after a character invests a certain number of points in a mastery path; for example, the life-draining Rune of Fortune is only available to someone who has spent 9 mastery points in the Path of Grungni.
The following abilities associated with the Path of Grungni are available to all Rune Priests regardless of points in that path:
Grungni's Gift: The first healing spell a Rune Priest gets, already on his action bar when he first enters the world, Grungni's Gift is an instant cast heal that restores a relatively small amount of health to a target. With its low cost of 25 action points, this is a readily spammable ability, but it seems pretty inefficient in terms of amount of healing done over time. Unless your target's health is dropping precipitously, my impression is that the heal-over-time Rune of Regeneration or the shield-and-minor-heal Rune of Shielding would be the better instant cast option.
Rune of Striking: Also available upon character birth, this is a direct damage spell with a 2-second casting time. It will be a Rune Priest's solo PvE staple damage spell, but the casting time makes it less useful in scenarios and RvR (2 seconds is a long time, and in most circumstances the Rune Priests should be using his time and action points to heal).
Oath of Rune Power: Available at rank 4, this is a Rune Priest's first buff. It provides a bonus to Strength and Intelligence for an hour, and can be activated to deal a moderate amount of elemental damage to a target. This is a DPS buff, as Strength affects melee DPS and Intelligence affects casting DPS (ranged DPS relies on Ballistic Skill). Intelligence also increases offensive spell crit chance and decreases the chance that a spell will be disrupted.
Rune of Fire: Available at rank 5, Rune of Fire provides an instant cast direct damage spell. The spell costs 40 action points, making it substantially less action-efficient than the 2-second cast Rune of Striking.
Rune of Restoration: This spell, available at rank 8, is an easily-disrupted 3-second direct heal that restores a large amount of health. I expect it to be the staple of Rune Priest PvE healing, and in RvR it's a handy way of dropping a huge heal on someone who needs it (assuming you're not being hit when you cast it - that cast time can stretch out to 5 or even 10 seconds if the caster is taking damage. This spells *hates* squigs).
Protection of the Ancestors: This buff increases a group member's wounds by a substantial amount for 60 seconds and heals him for that amount, effectively giving that player over 1,000 hit points for a minute. An instant cast spell, I expect this will be the premiere last-second lifesaver in RvR, and will be permanently up on the tank in large-scale PvE. The downside is its 3-minute cooldown time, which means there will be many times when a Rune Priest desperately mashes this button with no effect.
In addition, a Rune Priest can gain certain other abilities once he has invested some points into the Path of Grungni. These abilities are not automatically granted when the Rune Priest reaches the appropriate level of investment in the path; the Rune Priest must spend an additional point to activate each ability. To unlock every ability in the Path of Grungni would require spending 22 mastery points. However, a player is free to only unlock certain abilities, or even none at all, while still investing in the path to increase the effectiveness of the abilities associated with the path. Here, then, are the abilities that become available as a player ascends the Path of Grungni:
Runic Blasting: This tactic, available with 3 mastery points invested in the Path of Grungni, increases the crit chance of the Rune of Striking, the Rune of Fire, and Grungni's gift by 15%. This increased crit chance works synergistically with another tactic further up the tree, the Rune of Nullification, which places a potent 100% healing debuff on the victim of a critical attack. Anti-healing debuffs are apparently key to winning higher-level RvR engagements, but m instinct is that a Rune Priest should generally be more concerned with healing than with burning down a target; to the extent that a Rune Priest goes offensive, it should be for the benefit of his survivability, with knockbacks, stuns, and silences. There are plenty of damage dealing classes with their own healing debuffs that can do the dirty work while the Rune Priests keeps them vertical. That said, the crit bonuses here will be quite useful for solo Rune Priests.
Master Rune of Fury: Available with 5 points in the Path of Grungni, this provides a group mates within the area of effect with a powerful action point buff during the minute-long duration of the master rune. Groupmates have a 20% chance of regaining 50 action points when they use an ability; i.e., each ability use has an expected action point regen of 10 points. This master rune will make the casting Rune Priest decidedly popular in both RvR and PvE combat. At 25 action points with a 2 second casting time, a Rune Priest should be able to keep this effect up through most of a given combat. I have almost no experience with other classes, so I'm not sure how often they run out of action points, but my impression is that most people will drain their action point pools in the course of particularly frenzied RvR fighting. The extra action points provided by the Master Rune of Fury could provide the Rune Priest's group with the edge needed to eliminate an opposing group when both groups hit the action point wall.
Ancestor's Blessing: Following the action point-restoring theme of the Master Rune of Fury, this talent gives each healing ability a 25% chance to increase the beneficiary's action point pool by 50. Note that this will not affect the Rune Priest himself. If a Rune Priest picks up this talent while also laying down a consistent Master Rune of Fury, it's hard to imagine his group running out of action points. The two abilities together might even be overkill, although I suspect that the combination is probably the optimal way of keeping the group productive. My take is that a Rune Priest on the Path of Grugni ought to expect his groups to do noticeably more damage than a group equipped with a differently-specced Rune Priest. Groups with ambitions of stratospheric DPS may insist on a Grugni-specced Rune Priest.
Rune of Fortune: This 2-second cast time spell sucks a moderate amount of life out of your offensive target and transfers it to your defensive target. A player can purchase this ability once he spends 9 points in the Path of Grungni. This looks like a time-efficient way of fighting solo PvE battles, allowing the Rune Priest to keep himself up at the same time he blasts a target down. Outside of that context, though, I don't see this spell as being all that useful (but I'm happy to entertain arguments to the contrary).
Rune of Nullification: As mentioned above, this tactic causes critical hits to place a 100% healing debuff on the target, meaning that for the duration of the debuff, the target cannot be healed. As also mentioned above, this is a nifty ability that a diligent Rune Priest likely will not get much out of, at least in RvR combat. To reliably inflict the debuff involves casting multiple offensive spells, and casting multiple offensive spells means not casting healing or shielding spells during that time. For a Rune Priest looking toward solo PvP or maybe PvE who's invested the requisite 11 points in the Path of Grungni, this is not a bad ability, but for someone interested in his role in a group, it's probably better to let the DPS focus on the healing debuffs.
Rune of Binding: This instant-cast long range stun is one of the few Rune Priest CC abilities. Requiring 13 points in the Path of Grungni, it lets the Rune Priest stun an opponent for 3 seconds while dealing a moderate amount of elemental damage. The 20 second cooldown means it cannot be spammed, but a 3 second stun every 20 seconds can certainly throw an opposing group off its stride, assuming the Rune Priest has the time and action points to spare. Diminishing returns mean that this spell will lose some of its utility in one-on-one situations.
Rune of Ending: This Morale 4 ability, available only after a Rune Priest spends a significant time in combat, is an area-of-effect life drain that sucks a large amount of health out of nearby enemies and transfers that health to group members. The 30-foot range may limit the effectiveness of this spell, as in most situations the Rune Priest will not want to be standing in the midst of the action. If a player has already invested 15 points in the Path of Grungni, though, it's probably worthwhile to buy this for the occasions when it will be useful. Assuming a player can fire it off when there are a large number of enemies in range - around a flag in a scenario, for instance - it could provide an insurmountable advantage to the Rune Priest's group.
So there you have it: the Path of Grungni. Based on my limited experience, it looks like the must-haves in this path for a Rune Priest focused on increasing his group's effectiveness are the Master Rune of Fury and the Ancestor's Blessing tactic, both of which restore action points to allies (and, in the case of the Master Rune of Fury, to the Rune Priest himself). Investing in the tree will also upgrade some useful base abilities, particularly the Rune of Restoration and the Protection of the Ancestors buff. With 15 points in the Path of Grungni, the Rune of Restoration will heal 1125 health and Protection of the Ancestors will provide a minute buff of an extra 160 wounds, or 1600 hit points. The DPS impact of the action point regeneration might be enough to sway me to the Path of Grungni, but right now I'm inclined to follow a different path to provide a different kind of utility to my groups.
Next up: the Path of Valaya.