You control at least six creatures that can attack this turn.
An opponent cannot block and kill creatures you control.
Steps
Declare at least six creatures you control as attackers.
Ghalta and Mavren triggers, creating at least six 1/1 Vampire creature tokens.
Activate Phyrexian Altar five times by sacrificing five Vampires, adding ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .
Activate Najeela by paying ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) , untapping all attacking creatures, giving them trample, lifelink and haste, and gaining an additional combat phase after this one.