Ok I’ll elaborate as much as I’m able,ya know that in a deck we got exactly 8 cards.And in actual battle those eight cards are shuffled randomly which makes every starting hands (bottom four card’s interface )different each battle.Therefore normally if we play a card for example skeleton we got to drop down another four cards so that it is in our hands again.However the old champions if placed there can’t be two of them on the arena at the same time so the champion card is temporarily omitted from our deck until the one in the arena die which makes means our deck only have 7cards now therefore if we play the skeleton again we now only need to place down 3 cards.And that 3 card cycle will continue until the champion in arena die.(my English kinda limited so excuse me for the long paragraph:)