§ 369.3 Core Rules PDF (officieel)

Replacement Effects that apply to a unit as it enters the Board can be identified by describing how the unit enters, or by describing a game action that occurs “as” a unit enters. Example: Master Yi, Honed reads “I enter ready.” This applies a replacement effect to the way that units normally enter. The event of him entering exhausted is replaced by one where he enters ready. Example: Baron Nashor reads “As you play me, add the Baron Pit battlefield token to the board if it's not there already. If you do, I enter there.” The last sentence of his ability is a replacement effect that replaces the event of him entering at his original play location with him entering at the Baron Pit if it was created.