Yep, I hate it.I hate random effect tables, so I'm going in with that bias already. HOpefully it's a pleasant surprise!
The Undead Warlock is basically a non-crap version of the Undying. It's ... OK.
To be fair, you can roll for it whenever you want. You can and should roll for it at the start of the day, and after each short rest if you've already used it. It lasts until you finish a short or long rest.College of Spirits is interesting, but I don't like that Tales from Beyond takes both your bonus action and your action. Terrible for action economy. I feel like the Bardic Inspiration spending part of it should require no sort of action type at all and the tale activation take a bonus action.
I say add a Violin to the spellcasting focus as well.I like the looks of College of Spirits.
A skull or a candle as a spellcasting focus is nice flavour. Spirit Session allows the bard to get a familiar, and a steed -- without needing to devote spells from Lore Bard/Magical Secrets.
While summoning Undead mooks to provide support/flanking bonus in the middle of the total chaos that is happening.I'm not sure it has to be better than OK. An undead patron is a rich thematic pool to draw from that's been utterly wasted by how mechanically lacking the Undying Warlock was. If we're taking this as part of a package deal with the Class Features UA from last year, then Animate Dead is already on the Warlock spell list and you've got everything you need for a classic necromancer.
But speaking of the Class Features UA, I note that nothing in the Undead Warlock specifically keys off Eldritch Blast. It's just "Hit a creature with an attack" triggers. So you could definitely roll a Blade Pact Undead Warlock, take the new Eldritch Armor invocation, grab a weapon, and start stomping around the battlefield as a heavily armored death knight swinging a necrotic damage greataxe.
Huh. I read it as a medium/spiritualist class and thought both classes had a more "gothic horror" theme. YmmvOK WotC, first of all, scrap this spirit bard. Then, create an actual shaman class. If this subclass is a nod to the shaman class, then it's gonna suck as much as the PDK was a nod to the warlord.