To be put short :
- Hawkins has a deck of cards, like in Yu-Gi-Oh
- Hawkins has to choose a card within his
- Card can be at Hawkins advantage, but they can also be at his disavantage
- Tower card was most likely the last card as he was apparently forced to choose it
- Tower card means a sudden disruptive change or sometime the fall of all system(monarchy or what else)
- That card meant to Hawkins that the Yonko will fall, so here Hawkins accepted his defeat, that's why he praised Killer