Some Yellow Line Suggestions
Weakening Echoes of Battle: the critical defense debuff needs to be greatly increased, and suggest that it cap out with a -10% light damage mitigation buff. This would allow minstrels to debuff light damage resistance (along with Call of Orome) to the same extent that a LM debuffs fire damage with Raven/Benediction increasing their own damage but also providing an alternative to fire debuffs for wardens and hunters.
Melody Stance: should provide +10% finesse. Yellow minstrels need the finesse b/c they still need to be geared for healing, but now need to hit things as well and the Finesse trait is too far down the red line to be readily accessible.
Perfect ballad: replace the 3% power cost buff/debuff with 2% attack duration, reducing attack during for allies (capping at 10% if used 5 times) and increasing attack duration on foes if Strike a Chord is traited.
Strength of Helm Hammerhand should have the equivalent buffing strength of a red captain banner, but offer defensive and offensive bonuses instead. My preference would be to keep the existing bubble, but reduce the skill CD to 30s, with a +20% to tact/physical mastery buff applied to the target and +20% crit magnitude buff lasting 20s (when in Melody stance).
Word Spreads should be increased to +4 targets (assuming close proximity).
Call to Fate: as stated above please increase the radius of the fellowship effect to at least 10 meters, preferably 15m.
Call to Greatness: in my mind, this capstone should be as significant as captains’ oathbreakers in terms of buffing efficacy, but the current class specific buffs are problematic in that the importance of different class skills has/can change over time. My preference would be for this skill to reduce skill inductions by -15% for 15s and attack during by -5%, while increasing the duration of the following class specific skills by 5-10 seconds:
Hunter: Burn Hot
Champ: Controlled Burn
Captain: Time of Need
Warden: Recklessness
Lore Master: Sic ‘Em
Guardian: Warrior's Heart
Beorning: Call to Wild
Burgler: Coup de Grâce (effect)?
RK: Mystifying Flames? (I really have no idea what would be good for RKs or Burgs).
The CD for Call to Greatness would need to be increased to 3 minutes, given suggested increase in potency. If this is too much work, the skill should at least provide a nice (defensive/offensive) stat buff , such as a high critical defense bonus (~25%) combined with a 5-10% mitigation bypass bonus and/or critical magnitude buff.
Please keep in mind that stacking buff classes at the cost of DPS classes results in a loss of DPS in most cases. Also unlike Captain banner/OB/telling, yellow minstrel buffs are mostly limited to the fellowship they are in.