Every card that appeared in a top-cut list for each legend, at the highest copy count any single list ran. Own these and you can rebuild any of the sampled lists — or any hybrid of them.
Reading the tables. The number is the max copies seen (a 1-of in one list, 0 in another, 2 in a third → shows as 2). The bar is how many of that legend's lists ran the card at all. Rows tagged core were in every list. Champion cards are included in the main count so an extra main-deck copy shows up.
Separate tallies main deck and sideboard on their own (a card can be a 1-of main in one list and a 2-of side in another). Combined adds each list's main and sideboard copies together first, then takes the max — that's the number you need to own to build any one full list. Battlefields and runes are max-per-item too (runes will sum past 12; that's the range covering both splits).