[RPG] What happened in 1999

I don't have access to the books you mentioned, so I may be duplicating something here. But my initial thoughts are to use Forces as a conduit for Mind:

1. Depending on when and where your story is set, you could do Mind magic over a telegraph or telephone line by using the electrical impulses between you and the other person. You could send secret messages to the other person, read his mind to determine whether what he said was truthful, etc. (Without Forces and the wire, this would require Correspondence or close proximity to the other person, as per usual.) Of course, it depends on your gaming group how far you should take this. Gravity is under the purview of Forces, but would it really be fair to say you can read anybody's mind anywhere on the planet because they're in contact with the same gravity as you? Probably not.

2. Make a lantern or candle perform some Mind effect on whoever sees its light. (Light is a force.) With Prime, this could become a "set it and forget it"-type spell. Otherwise, you may have to remain near the object. The Mind effect should be less powerful as the light gets dimmer or farther away. Alternatively, the effect could incur a Willpower roll. When the light is bright or close by, the difficulty is high. When the light is dim or far away, the difficulty is lower or the effect is nonexistent. Correspondence could help negate the distance problem.

3. You're a shop-keeper with a bell above your door. Cast a spell on it so that it chimes sweetly when most people enter your shop, but it takes on a discordant tone when someone enters who (intends to do something bad, is in disguise, hasn't bathed, etc.). You could channel this as long as you're near the shop's entrance, or use Prime to set and forget.

4. This doesn't combine the two spheres into one effect, but it still makes use of both of them in the same scene: When speaking in front of a crowd, use Forces to amplify your voice, and use Mind to sway your audience to your point of view.

It may also be possible to use Mind as a conduit for Forces:

1. When someone tries to use Mind magic on the target of this effect, they're met with either extreme heat or cold in their head. Not the perception of heat or cold, as that would just be Mind, but true, damaging heat or cold. Throw in a bit of Life, and you could disrupt their body's inherent electrical impulses and stop their brain or heart.

The 4e FR Campaign Guide is completely silent about the topics you raise. Neither Dendar, nor Ubtao appear in its index. To the extent that I could track, Dendar is mentioned only one time in name as a primordial, and one more time as simply the Night Serpent while the Shadow Epoch (before -35000DR) is discussed. The Shadow Epoch is also the only time we hear about Ubtao the Deceiver, as the traitor who sided with the elder gods against fellow primordials. 4e FR Player's Guide has nothing at all regarding these topics; I could not identify a single instance where their names appear at all.

The main things we know from these two 4e books is that Chult became a separate island of its own after the Spellplague and the merging of Abeir and Toril. Mezro turned into a pit that was being haunted by various undead.

The 5e Sword Coast Adventurer's Guide is also thin in terms of information regarding Chult. Sadly the Second Sundering has not restored Mezro, it is still described as a ruined city haunted by the undead. Ubtao is not mentioned in the book (does not appear in the index), and Dendar is only mentioned as one of the possible warlock patrons; and is described to be from the Far Realm of the Great Old Ones.

In short, I don't believe there are RAW answers to your question(s) in the campaign settings. Dendar does not appear to have been released though, and it has not become a deity.

Finally, according to the recent 5e adventure Tomb of Annihilation, (spoilers ahead):

9 primal spirits came to be worshipped as gods after Ubtao's departure, but they were then destroyed by Greyhawk's infamous demilich Acererak, so it is unclear how much the FR designers want to continue the Ubtao-Dendar story for the future of Chult. However we also read that Ubtao left because of strife amongst his followers and their over-reliance on him, that yuanti are planning to open a portal to free the Night Serpent, and that Mezro planeshifted, so there may be more to come.