That's 4
Borderland Ranger (Human Scout, 2/2, When Borderland Ranger enters the battlefield, you may search your library for a basic land card, reveal it, and put it into your hand. If you do, shuffle your library.)
Response or can I search?
Spidey: 10
Hand: 5
Library: 29
Battlefield:
(U,U,U,U) Swamp x4
(U,U) Piranha Marsh (~ ETB Tapped.; When ~ ETB, target player loses 1 life.; T: Add B to my mana pool)
Graveyard: Vampire Nighthawk
Exile:
Mooseman: 18
Hand: 4
Library: 28
Battlefield:
(UUU) Mountain x3
(UU) Forest x2
(T) Forest (4/5 Treefolk)
(U) Greenweaver Druid (Elf Druid, 1/1, {T}: Add {G}{G} to your mana pool.)
(U) Awakener Druid (Human Druid, 1/1, When Awakener Druid enters the battlefield, target Forest becomes a 4/5 green Treefolk creature for as long as Awakener Druid is on the battlefield. It's still a land.)
Graveyard: Terramorphic Expanse, Lightning Bolt
Exile: