Blighted Woodland

{T}: Add {C}.
{3}{G}, {T}, Sacrifice this land: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Arena

{3}, {T}: Tap target creature you control and target creature of an opponent's choice they control. Those creatures fight each other. (Each deals damage equal to its power to the other.)

Grothama, All-Devouring

Other creatures have "Whenever this creature attacks, you may have it fight Grothama, All-Devouring."
When Grothama leaves the battlefield, each player draws cards equal to the amount of damage dealt to Grothama this turn by sources they controlled.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Forest

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.