Jegantha does not have summoning sickness.Dean of Order.
An opponent cannot block and kill
Jegantha.
Steps
Declare
Jegantha and any other desired creature(s) as attackers.
Augusta triggers, as well as
Najeela for each Warrior that was declared an attacker.
Resolve the
Najeela trigger(s), if applicable, creating that many 1/1 Warrior creature tokens that are tapped and attacking.
Resolve the Augusta trigger, untapping all creatures you control.
Activate
Jegantha by tapping it, adding ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) that cannot be spent to pay generic mana costs.
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.