Borderland Behemoth

Trample
Borderland Behemoth gets +4/+4 for each other Giant you control.

Sunrise Sovereign

Other Giant creatures you control get +2/+2 and have trample.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Mountain

Dreamstone Hedron

{T}: Add {C}{C}{C}.
{3}, {T}, Sacrifice Dreamstone Hedron: Draw three cards.

Thundercloud Shaman

When Thundercloud Shaman enters, it deals damage equal to the number of Giants you control to each non-Giant creature.

Stinkdrinker Daredevil

Giant spells you cast cost {2} less to cast.

Iron Myr

Giant Harbinger

When Giant Harbinger enters, you may search your library for a Giant card, reveal it, then shuffle and put that card on top.

Hamletback Goliath

Whenever another creature enters, you may put X +1/+1 counters on Hamletback Goliath, where X is that creature's power.