2023-04-14 : It doesn’t matter if the creatures that convoked Knight-Errant of Eos are still on the battlefield or not as the enters-the-battlefield ability is resolving. You’ll get credit for them when determining the value of X.

2023-04-14 : You can’t tap more creatures to convoke Knight-Errant of Eos than is necessary to pay for the spell. In most cases, this means five creatures. However, if there are any additional costs to cast Knight-Errant of Eos, you may use convoke to pay those additional costs as well.