First thing is that it's a 3-card combo.
Second thing is that it has to be at least as likely to get you behind on FG as ahead? Or roughly so? Which is still really good if you want to use talisman for other stuff, but bad otherwise. Which really makes it at least a 4 card combo...
Because, let's break it down now (cue MC Hammer)
Best-case: you get hamlet and talisman together on turn 3-4, with 3 other coppers. You get 4 FG in one turn, and win the split 6-4 or 7-3. This is pretty rare, happening... just over 5% of the time? Does someone want to do exact math here?
Also Possible: You get hamlet and talisman together without 3 more copper. You get 2 FG in one turn, 1 in another, and either split the FG or maybe win 6-4 with a little luck. This will happen maybe ~20% of the time.
Otherwise you're either missing one of them to the reshuffle, which can always happen, (and around a quarter of the time, it will here), or you get the talisman on one turn (2 FG) and:
hamlet with 4+ coppers out of 5 cards, 2 more FG, happens ~25% of the time;
Hamlet with only 2-3 coppers, only 1 FG, happens ~ 25% of the time.
So, in terms of winning the FG split, it's... a bit worse than just buying them/a lot worse than talisman/FG? And of course if these cards are otherwise useful, than yes, it will be good. If not, it's risky, and I... wouldn't go for it, probably, because I don't want the talisman, or I do want the talisman but the hamlet is too big a risk. If there's another useful $2, or you really want the hamlet at some point and a talisman to pick something up at some point, than definitely go for it.
But I guess I'm saying a bit too niche for a combo article.
edit: Still good to talk about though!
edit2: I can't do math!