River Boa

Landwalk is a generic term that appears within an object’s rules text as “[type]walk,” where [type] is usually a land type, but it can also be the card type land plus any combination of land types, card types, and/or supertypes.

Landwalk is an evasion ability.

A creature with landwalk can’t be blocked as long as the defending player controls at least one land with the specified land type (as in “islandwalk”), with the specified type or supertype (as in “artifact landwalk”), without the specified type or supertype (as in “nonbasic landwalk”), or with both the specified type or supertype and the specified subtype (as in “snow swampwalk”). (See rule 509, “Declare Blockers Step.”)

Landwalk abilities don’t “cancel” one another.

Multiple instances of the same kind of landwalk on the same creature are redundant.

If the effect of a resolving spell or ability regenerates a permanent, it creates a replacement effect that protects the permanent the next time it would be destroyed this turn. In this case, “Regenerate [permanent]” means “The next time [permanent] would be destroyed this turn, instead remove all damage marked on it and its controller taps it. If it’s an attacking or blocking creature, remove it from combat.”

If the effect of a static ability regenerates a permanent, it replaces destruction with an alternate effect each time that permanent would be destroyed. In this case, “Regenerate [permanent]” means “Instead remove all damage marked on [permanent] and its controller taps it. If it’s an attacking or blocking creature, remove it from combat.”

Neither activating an ability that creates a regeneration shield nor casting a spell that creates a regeneration shield is the same as regenerating a permanent. Effects that say that a permanent can’t be regenerated don’t preclude such abilities from being activated or such spells from being cast; rather, they cause regeneration shields to not be applied.