(: Add or to your mana pool.)
As Watery Grave enters the battlefield, you may pay 2 life. If you don't, Watery Grave enters the battlefield tapped.
10/1/2005 Has basic land types, but isn’t a basic land. Things that affect basic lands don’t affect it. For example, you can’t find it with Civic Wayfinder.
10/1/2005 If another effect (such as Loxodon Gatekeeper’s ability) tells you to put lands onto the battlefield tapped, it enters the battlefield tapped whether you pay 2 life or not.
10/1/2005 If multiple permanents with “as enters the battlefield” effects are entering the battlefield at the same time, process those effects one at a time, then put the permanents onto the battlefield all at once. For example, if you’re at 3 life and an effect puts two of these onto the battlefield, you can pay 2 life for only one of them, not both.