Brazen Buccaneers
Oracle Text
Haste
When Brazen Buccaneers enters the battlefield, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)
Card Rulings
1/19/2018 Once an ability that causes a creature to explore begins to resolve, no player may take any other actions until it’s done. Notably, opponents can’t try to remove the exploring creature after you reveal a nonland card but before it receives a counter.
1/19/2018 If no card is revealed, most likely because that player’s library is empty, the exploring creature receives a +1/+1 counter.
1/19/2018 If a resolving spell or ability instructs a specific creature to explore but that creature has left the battlefield, the creature still explores. If you reveal a nonland card this way, you won’t put a +1/+1 counter on anything, but you may put the revealed card into your graveyard. Effects that trigger “whenever a creature you control explores” trigger if appropriate.
A 3/3 with haste and a better version of Scry 1 for 4 CMC. Good.
A 2/2 with haste that adds a land to your hand in red for 4 CMC. Also good.
It's no Snapcaster Mage, but it's pretty efficient, especially considering it's a common.