The Warsong Drummer is an archetype for the Skald Class. It is part of the Shards of Power playtest, the whole google doc can be found here

Warsong Drummer

The thrum of battle echoes wherever a Warsong Drummer treads. Their very presence emboldens allies and causes enemies to cower in fear. Lightning and thunder strike at their command and tides of battle turn at their will.

Class features modified or replaced by this Archetype: Bardic Knowledge, Song of Marching, Dirge of Doom, Lore Master, Damage Reduction.

The Drums of War (Su): At first level the warsong drummer can use the beating drum they feel in their heart to harm their foes. They learn to shape the Twin Thunders veil. They treat their class level as their veilweaving level, their Charisma as their Veilweaving modifier, and increase their number of veils shaped by 1.
At 4th level they treat this veil as if it were bound to the Hands chakra for determining its effects.
This replaces the Bardic Knowledge class ability.

Essence Pool: The warsong drummer gains 1 point of essence at 1st level and every 3 levels thereafter.

Raging Song: The Warsong Drummer has a deeper connection with the way their music affects the spirits of others. They learn the Inspired Rage, Song of Strength, and Song of the Fallen performances as normal but otherwise learn the performances below:
  • Song of the Blessed (Su): At 3rd level the Warsong Drummer learns to use his performance to draw out the truth he sees in his allies to grant them strength. At the beginning of each day when they shape their Twin Thunders veil they may select a single veil with the [title] descriptor. While performing this song they may choose a single ally within 60 ft. and treat them as if that title veil were shaped upon them. This song may be invested with essence, causing any veil it grants to be treated as if it were invested with that essence.
    This replaces Song of Marching.
  • Song of the Cursed (Su): at 10th level the Warsong Drummer learns to use his performance to draw out the flaws he sees in his enemies to cripple them. At the beginning of each day when they shape their Twin Thunders veil they may select a single veil with the [brand] descriptor. While performing this song they may choose a single enemy within 30 ft. to target with that brand veil. Affected enemies may save against its effects as normal if the veil allows a save. If all affected enemies pass this save and the brand is not applied, this performance still costs one round of bardic performance. This song may be invested with essence, causing any veil it grants to be treated as if it were invested with that essence. Affected targets are only under the effects of these brands while they remain within 30ft.
    This replaces Dirge of Doom.

*Special: for the purpose of feats like Skald’s Vigor and Greater Skald’s Vigor treat the essence invested in these songs as the strength bonus provided.

Escalating Percussion (Su): At 7th level the Warsong Drummer begins to understand that his songs do more than fan the hearts of allies and chill the blood of his foes, they bring them a step closer to the ideal state they see in them. Starting at 7th level they may select a second ally to be affected by their Song of the Blessed and grant them the effect of the title veil chosen. At 13th level they may choose a third ally to gain the effects of the chosen title.
At 15th level the Warson Drummer may choose a second enemy to be affected by their Song of the Cursed chosen brand and finally at 20th level they may choose a third enemy to be affected by the chosen brand.
This ability replaces the Lore Master and Damage Reduction class features.

Improved Essence Capacity: The warsong drummer listens to the beat of his heart, and the world accompanies it. At 8th level and 16th the maximum essence capacity of all their receptacles increases by 1.