Syr Faren, the Hengehammer

Legendary Creature — Human Knight

Whenever Syr Faren, the Hengehammer attacks, another target attacking creature gets +X/+X until end of turn, where X is Syr Faren's power.

2/2

2019-10-04:
The value of X is determined only as Syr Faren’s triggered ability resolves. Once that happens, the value of X won’t change later in the turn even if Syr Faren’s power changes.
2019-10-04:
If Syr Faren leaves the battlefield before its triggered ability resolves, use its power as it last existed on the battlefield to determine the value of X.
2019-10-04:
If Syr Faren’s power is negative as its triggered ability resolves, X is considered to be 0.