The official Story page, along with these two videos sums up how it happened
Dealing damage with The Eleventh Doctor lets you exile a card from your hand, putting time counters on it equal to its mana value, and giving it suspend
Combos are now usually discussed as part of the typical Rule 0 conversations beforehand as these skew you toward competitive rather than casual Commander games
Short interviews with CEO Wenzel Krautmann , Buying Lead Lukas Schwendinger , and Listing Lead Gerhard Saldinger cover speed (often seconds per card), consistency (strict, not picky), and the escalation path when a fake is suspected
Even better, you can then place a permanent from your hand onto the battlefield for free
General Leo Cristophe* If Leo cost a bit less mana hed be much higher up on this list, as at 5 mana returning one cheap creature, and growing based on how many creatures you have is just not that good especially given he lacks any protection or evasion