Devastating Summoning

Sacrifice any number of creatures that are different colors of mana
Search your library for a creature card, with same
color as the first creature sacrificed, and place it in
your hand. If that creature was legendary, place all creatures of that same subtype in play with haste.
If those creatures are Red, create a 5/5 Red Dragon
for each creature in play. Creatures you control get +1/+1 for each creature sacrificed and they gain all their abilities until end of turn.