Najeela and Shriekwood Devourer on the battlefield.
You control up to five lands that can tap to produce at least ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .
You control a creature with power 5 or greater that does not have summoning sickness, and that cannot be blocked and killed by an opponent.
Steps
Declare any creature with power 5 or greater that cannot be blocked and killed by an opponent as an attacker.
Shriekwood Devourer triggers, and Najeela triggers if a Warrior attacked.
Resolve the Najeela trigger, if applicable, creating a 1/1 Warrior creature token that is tapped and attacking.
Holding priority, activate up to five lands by tapping them, adding at least ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .
Resolve the Shriekwood Devourer trigger, untapping at least five lands.
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.