Yes I think you have the chance to fail unless GM, but if you are Ozzy tanking... I wouldn't rely on needing to heal yourself as much. Depending on the target, you may need to be spam healing your ozzy the entire time anyways. I think the whole idea with this build is to avoid taking damage to your own character.
Tactics at GM is super important, in fact I think going from 80 to 100 Tactics gives you more of a damage boost than going from 80 to GM Lumberjacking. Regarding Archery, it's not necessary with good positioning (monsters will always attack the nearest enemy to them, and they consider N, S, E, and W to be "1" tile from them and NW, NE, SE, SW to be "1.5" tiles from them, so just make sure you're diagonal and your pet is perpendicular). But with the to-hit formula on this shard, archery has a similar DPS stationary at 2 tiles away as some of the faster and harder hitting weapons. I think Macing might be fun, as a way to help out your pet by knocking off some stamina from the enemies and making them hit your pet more slowly. 100 Vet 100 Animal Lore 100 Magery 100 Macing 100 Tactics 100 Anatomy 100 ???? Plenty of fun flexibility for that last slot. And if you really want to go with a wacky template, try: 100 Vet 100 Animal Lore 100 Magery 100 Macing 100 Tactics 100 Music 100 Discord I suspect the Discord reduction in HP and stats will be similar to the damage bonus you'd get from Lumberjacking and Anatomy. Plus it will make your enemies far less damaging to your pet.
This looks like fun! I'm also going to be rolling with sub-GM Tactics. I'm sure you know already, but one thing to note is that doing so is only really advisable with exceedingly accurate/supremely accurate weapons. That does become costly. Edit: just saw Keza's post with ^^that^^ info! My bad! I'll also be experimenting with sub-GM lumberjacking; probably 90. But, why lumberjacking for you? Why not a mace fighter? The stun/stamina would benefit your ostard's survivability. Fencing might be nice, too, for a quick escape. Paralyze with the spear and then run or ride away from a bad situation. Converting Swords + Lumber into Macing or Fencing also frees up a hundred points! I'm not certain on Animal Lore's mechanics, so take the following with a grain of salt: does it need to be 100.0 to estimate your ostard? If its only purpose is to do that but it can do it reliably at a lower level, then it should be sub-GM (imo). Between resisting spells and Healing, I, personally, would choose Healing. You won't be taking a bunch of direct damage from anything since you have a tank, but occasional hits might be a problem. Important to get that damage restored asap, and being able to do so without disarming (as you would have to with a potion) seems ideal. Finally, why 30 magery? It seems to incur a high fizzle chance even for low-level spells.
High rate of success to recall off of recall scrolls, this is to avoid that "Oh poo a PK" moment, due to this build not setup for such a fight. Of course if you only hunt in rarely frequented areas or instances you can drop the Magery to 10 and and boost tactics to 100. You can still recall like 15% of the time with 10 magery off of scrolls