River Shaper

{t}{u}{u}: Create a 1/1 River Bird with flying
{t}{u}{u}{u}{u}: Create a 2/2 River Avatar with
lifelink
{t}{u}{u}{u}{u}{u}{u}: Create a 5/3 River Dragon with
flying
{t}{u}{u}{u}{u}{u}{u}{u}: Create a 4/5 River Giant
with trample and hexproof