5e Wild Talent Feat - How to Affect Damage Roll?

Please excuse me if this isn't the place to post, but I haven't found a post on this yet. I have a player wanting to use the new Wild Talent feat in the Unearthed Arcana with a maul, and I'm looking for how to have him roll his damage correctly in Roll20 (without an API, though a token action / macro would be fine). When he swings his maul, it deals 2d6 damage. This feature would allow him to roll a third die and, if it is higher than one of the other two, replace it. He's still only keeping 2 dice. The kicker here is that the size of the die can change - it ranges from a d4 to a d10, and shrinks and grows based on how it is rolled (shrinks if it rolls the highest number on the die, grows if it rolls a 1). I can't think of a way to simulate this in a less cumbersome way than have it roll 2d6 on one damage type and then the other die on another damage line, then manually compare. Any ideas? Thanks in advance!

Yeah, that can be done with a string like this put in the damage field: {1d6, 1d6, ?{Psychic Talent Die Size|1d10|1d8|1d6|1d4}}kh2 I'd caution against it, though, as I'd imagine character has more than one attack (based on the level and martial weapon proficiency) and that particular use of the Psychic Talent is only usable once per turn. It's meant to be used after the damage is rolled in case the player thinks they can do better.

I think that helps out a lot. I'm still trying to learn everything. Thank you!

How about 3d6kh2?

Patrick - the issue is that the size of the die can change throughout a session.

Dakota’s method then but maybe saved as a separate ability on the attributes and abilities tab.  Since it’s only once a turn and not every attack.  That way it can be used separate from a normal attack.

If it were me, I would set up a normal attack and then a separate one for each die size so all I have to do is click once to roll. But I'll run this by my player and see what he wants. Thanks all!