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.)

Thawing Glaciers

Thawing Glaciers enters tapped.
{1}, {T}: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. Return Thawing Glaciers to its owner's hand at the beginning of the next cleanup step.

Prahv, Spires of Order

{T}: Add {C}.
{4}{W}{U}, {T}: Prevent all damage a source of your choice would deal this turn.

Tower of the Magistrate

{T}: Add {C}.
{1}, {T}: Target creature gains protection from artifacts until end of turn.