Realm Seekers

Realm Seekers enters with X +1/+1 counters on it, where X is the total number of cards in all players' hands.
{2}{G}, Remove a +1/+1 counter from Realm Seekers: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Foundations Jumpstart

Tales of Middle-earth Commander

Realm Seekers enters the battlefield with X +1/+1 counters on it, where X is the total number of cards in all players' hands.
{2}{G}, Remove a +1/+1 counter from Realm Seekers: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Commander 2016

Realm Seekers enters the battlefield with X +1/+1 counters on it, where X is the total number of cards in all players' hands.
{2}{G}, Remove a +1/+1 counter from Realm Seekers: Search your library for a land card, reveal it, put it into your hand, then shuffle your library.

Vintage Masters

Conspiracy

If Realm Seekers enters the battlefield directly from a player's hand without being cast, it counts itself when determining the value of X.

The value of X is determined as Realm Seekers enters the battlefield. Players can cast spells and activate abilities while Realm Seekers is on the stack to remove cards from their hands if they wish, and this will result in fewer counters being placed on Realm Seekers as it enters the battlefield.