Originally from Chicago, with live tournament cashes dating back to as early as 1999, Kastle has a daunting 356,800 chip stack to take with him into Day 2 tomorrow - nearly 100k ahead of second-place Nikola Sears.
It took a huge hand at the very end of the day to put him there though.
According to the WPT live updates, Kastle was set to finish the day with about 170k when a massive hand with chip leader Michael Tureniec materialized.
Tureniec had just been moved to the table with a 280k stack and found himself with pocket queens.
Kastle had aces and, after a six-bet shove, got a call from Tureniec.
Kastle held and swept the chips in to grab the big lead. Tureniec survived but was knocked down to just 100k.
Anticipation was high for a big turnout in Prague on Day 1b after a booming Day 1a and a rebuy option for players who busted.
The anticipation was warranted as another 337 runners bought in to make for a record 568-player field and break the record for biggest WPT event in Europe ever.
With a buy-in of €3200+€300, the prize pool is a healthy €1,753,200 with six-figure scores for the top four finishers and €450,000 for the winner.
The rebuy option worked out well for several players as well, most notably American Steve O’Dwyer, who busted on Day 1a but returned to the casino and built himself a massive stack of 241,000 to head into Day 2.
O'Dwyer sits in fourth overall.
Other notables advancing from Day 1b with a decent stack include the UK’s Martins Adeniya (205,000) and Daniel Carter (142,500), tour veterans Mike “Timex” McDonald (103,500) and Eugene Katchalov (101,500) and Basil “French durrrr” Yaiche (87,500).
Joining the Day 1b crowd at the top of the leaderboard are Day 1a leaders Jan Ramik (209,300) Jan Bandik (180,400) and Eron Malkin (169,200).
Notables to bust out today included Chris Moorman, Shannon Shorr, Harrison Gimbel, Andy Frankenberger, Roberto Romanello, Marvin Rettenmeier, Toby Lewis and Melanie Weisner.
The 124 who survived Day 1b will join the 93 from Day 1a when Day 2 kicks off at 2 p.m. tomorrow (CET).
Follow the action live at WPT.com.