Land Amalgamation

When this card enters the battlefield, you must sacrifice a Plains, Island, Swamp, Mountain, and Forest.
{t}, Add five mana of any color to your mana pool.
{w}{t}, Summon 3 white 1/1 Knight creature
tokens.
{u}{t}, Counter target spell.
{b}{t}, Regenerate target creature.
{r}{t}, All attacking creatures gain Double-Strike.
{g}{t}, You gain 5 life.