Serum Powder

{T}: Add {C}.
Any time you could mulligan and Serum Powder is in your hand, you may exile all the cards from your hand, then draw that many cards. (You can do this in addition to taking mulligans.)

Gingerbread Cabin

({T}: Add {G}.)
Gingerbread Cabin enters the battlefield tapped unless you control three or more other Forests.
When Gingerbread Cabin enters the battlefield untapped, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Forest

Silvos, Rogue Elemental

Trample
{G}: Regenerate Silvos, Rogue Elemental.

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Lost in the Woods

Whenever a creature attacks you or a planeswalker you control, reveal the top card of your library. If it's a Forest card, remove that creature from combat. Then put the revealed card on the bottom of your library.