It would need to be checked on RealUO (I cant get access to the masteries on EJ) but that information is from publish 66, which was adjusted in 67:
Which i am not going to go through and verify each, nor am i going to go through each publish to see if it was adjusted again, which is why i say it just needs to be tested on RealUO, as far as interrupted.i believe they meant while casting it, not while maintaining it,or might have been an old feature as it seems like a bard was originally not even able to cast while channeling. so again i would hope things are not adjusted based on that UO link, as it is clearly not accurate as i have shown in the link and the video.
Bard Changes
- Bard spell songs are no longer interrupted by spellcasting.
- Bards with either provocation or peacemaking mastery can have both their mastery spell songs active at the same time.
- Bards with secondary bard skills above GM (Real Skill) will receive a slightly reduced mana cost for spell song upkeep.
- Bards with a mastery get a 5% bonus to their success chance at using any bard skills, and a 10% bonus to using the skill of their mastery focus.
- All bard songs receive a slight bonus to their effects if the bard has additional bard skills over GM(Real Skill).
- Discordance spell songs are now affected by the target's magic resistance. (PvP and specific Mobs only)
- Despair Damage Tweaked: 1.5x vs Non Player, 3x Damage with Slayer Instruments.
- Tribulation: Damage bonus modified by 1.5 with Instruments.
- Bard Skill Timeout reduced to 8 Seconds.
- Having a bard mastery reduces all Bard Skill Timeouts by 1 second, and an additional second for the Skill of the mastery focus.
Which i am not going to go through and verify each, nor am i going to go through each publish to see if it was adjusted again, which is why i say it just needs to be tested on RealUO, as far as interrupted.i believe they meant while casting it, not while maintaining it,or might have been an old feature as it seems like a bard was originally not even able to cast while channeling. so again i would hope things are not adjusted based on that UO link, as it is clearly not accurate as i have shown in the link and the video.

