Drill Man, Eradication Navi

Artifact creature's you control have Basic
Landwalk. (This creature is unblockable if defending player controls a basic land)
If Drill Man, Eradication Navi deals combat
dammage to a player, that player sacrifice's
a land and discards a card.
Sacrifice a Mountain: Drill Man, Eradication Navi becomes indestructible untill end of turn