16 Jun 2023
To determine how many additional +1/+1 counters a creature enters the battlefield with, use Arwen, Weaver of Hope's toughness as that creature is entering the battlefield.
16 Jun 2023
If Arwen, Weaver of Hope and another creature you control enter the battlefield at the same time, Arwen's ability won't cause that creature to enter with additional +1/+1 counters on it.