This is a Boros Midrange deck designed for the M14 Transition; most cards in it are not rotating out in Theros.
As the name implies this deck is designed around triggers; originally it was just about a top-down build around Firemane Avenger and other Triggered abilities, it seems like Strionic Resonator is the new flagship of this deck since all the triggers contained within can now be duplicated on an as-needed basis!
Here's a breakdown of useful resonator triggers in this deck:
Guttersnipe - copyable 2 damage to opponent
Tablet of the Guilds - copyable 1 or 2 life gain
Firemane Avenger - copyable lighting helix
Tajic - copyable +5/+5 pump
Assemble the Legion - copyable muster counter + soldier tokens trigger, resulting in an exponential increase in soldier production (instead of 1, then 2, then 3, then 4 you would get 3, then 7, then 11, then 15 this can get out of hand VERY quickly)
Zealous Conscripts - copyable "act of treason"
Aurelia - copyable extra combat phase
Archangel of Thune - copyable +1/+1 counter added to each creature on any lifegain event
Ring of Oblivion - copyable exile (it's a "enter the battlefield" trigger so you can exile as many target permanents as you can resonate!)
Christmas Combo:
Firemane Avenger, Archangel of Thune, Aurelia and 1 Strionic Resonator on the battlefield.
Swing with all, use Strionic Resonator to copy Aurelia's extra combat phase.
Lightning helix triggers 1 lifegain event, dealing 3 damage and gaining 3 life.
Firemane Avenger hits as a 4/4 flyer
Archangel of Thune hits as a 4/5 flyer
Aurelia hits as a 4/5 flyer
Add 1 more +1/+1 counter to all creatures and repeat.
lightning helix triggers 1 lifegain event, dealing 3 damage and gaining 3 life.
Firemane Avenger hits as a 6/6 flyer
Archangel of Thune hits as a 6/7 flyer
Aurelia hits as a 6/7 flyer
Add 1 more +1/+1 counter to all creatures and repeat.
lightning helix triggers 1 lifegain event, dealing 3 damage and gaining 3 life.
Firemane Avenger hits as a 8/8 flyer
Archangel of Thune hits as a 8/9 flyer
Aurelia hits as a 8/9 flyer
Add 1 more +1/+1 counter to all creatures.
final creature sizes: 9/9, 9/10, 9/10
Total Damage Dealt: 60
Total Life Gained: 24
Some other cards that do not exist in this deck, but may be possible strionic resonator combos:
Ordruun Veteran - Copy double-strike trigger and apply it to another creature (a pseudo silverblade paladin)
Boros Reckoner - copyable damage reflection trigger (really would prefer this creature to frontline medic or guttersnipe, but alas I have none)