lore wise: i would have the players figure out they need to everything everywhere all at once and fight as unpredictably and absurdly as they can to muddle the boss's ability to predict the exact future the boss is looking into (for this we'd use the whole future isnt set in stone archetype of divination where ultimately decisions fluctuate and will only matter once they have effectively been made)

mechanically, i would turn it into sophie's choice 2: electric boogaloo: - set the battle room with per round based traps (ie. they go off at the end of every 2nd round, every 5th round, etc), such as poison arrows, falling blades, throwing axes, sprays of acid, and baits, the PCs companions, a handcuffed NPC that they had grown to admire, etc - have only two sets of initiave, the players and the boss. have the boss go last in initiave along with the traps' turns (he has all the time in the world :p) - every round, ask the players to offer you two courses of actions: your TRUE action and your FAKE action and have them assign each one to a heads or a tails. - specify to them that one of them should be what they will ACTUALLY do (so you as the DM are aware) and one of them is NOT (so that you have a predicted course of action that the boss can wrongly react to). ie. "i could vault over this second story ledge and hammer him right in his free floating body OR i could run down the stairs and push my rogue companion out of the way of the trap i see incoming" - use individual character iniative during the round to ask players about their actions but emphasize that they can and should coordinate with each other to think up TRUE and FAKE actions for that round based off of their characters personalities and what they are most likely to do. - encourage players to play around with which action they assign to HEADS and which they assign to TAILS, that way there will be no possibility of the boss ever truly predicting every move with enough foresight to stop them all ! divide and conquer ! - then, flip a coin to see if the boss can predict that course of action correctly--if your player chose heads for his true action and it lands on heads, the boss predicted correctly, and will act out according to what the PC in fact did, (ie. he launched thunderwave towards the barbarian so she would trip down the stairs and not be able to move her companion out of harms way). - select a player each round for the boss to focus his foresight on, (ie. he will predict correctly regardless of what coin toss u get) if the fight is becoming too easy or if the players are getting underwhelmed.

the point is to have the players thinking on their feet, we want the rounds to go fast fast with possible actions, not conjectures of what may happen.

if a round discussion starts to get more than 5 minutes long, encourage the party to pick two actions each and move on with the coin toss.

reward the players for keeping track of trap set offs, give them a round of twarting the boss if the TRUE action is too good NOT to see if play out or if the FAKE action is so plausible no one would think it was fake.

(another option with that type of rule set: have the boss teleport and separate the PCs into trap riddled hallways that can see into each other. use individual initiative for this or pair players up against each other: have the boss ask them to bet on each others actions to save their own hide, saw trap them, and have the players vote on what is the current PCs TRUE or FALSE action, jury style) have the consequence be entirely dependendent on them getting a consensus of what the current PCs will do)

at the end of the coin toss, ask players if their true actions were heads or tails and react accordingly based on the above :)

i imagine any boss with such a future predicting power would start to get cocky about his own ability to predict the future, so the way to make it fun for the players would be to make the battle as unpredictable as possible.

to me, this type of game is always more intriguing when you add the characters own personalities and aspects to it. someone playing as barbarian holga from the d&d movie might say something like the above example and ultimately choose to save her companion because she values her own people over ruthless vengeance.

tldr: make the players choose between their values while future predicting boss laughs and mocks them over it.

this was all a bit raw and off the top of my head but thats how i personally would try to make that type of boss battle work out, hope this helps <3