While the guide was posted and ready, I didn't actually participate during this Holiday as much as I could have. My heart wasn't in it for more than just getting the new Toys out of this round, but I did manage to collect another meta achievement on one of my alts.
I'm going to forego adding the percentage chance of completion at the next outing of the Holiday events. Those percentages are usually wrong, unless I absolutely want to get something from that Holiday.
Paragon the Warrior: Elder of '09.
Railene the Paladin: Elder of '10.
Xardion the Death Knight: Elder of '10,
Laviana the Mage: Elder of '11.
Arcia the Druid: Elder of '11.
Sollexi the Rogue: Elder of '12.
Ferenan the Monk: Elder of '16.
Yesira the Blood Knight: Elder of '16.
Disana the Shaman: Elder of '17. Completed all available achievements and collected the three new Toys; Dragon Head Costume, Dragon Body Costume, Dragon Tail Costume.
Zaliah the Hunter: Unofficial Elder of '09 due to account-wide achievements.
Mytheasia the Demon Hunter: Unofficial Elder of '09 due to account-wide achievements.
Vanetti the Demon Hunter: Unofficial Elder of '09 due to account-wide achievements.
Lillidan the Demon Hunter: Unofficial Elder of '09 due to account-wide achievements.
Leriss the Paladin: Unofficial Elder of '09 due to account-wide achievements.
Buki the Hunter: Unofficial Elder of '09 due to account-wide achievements.
Elamshin the Warrior: Unofficial Elder of '09 due to account-wide achievements. Secondary account does not currently have Legion, if new content is added in '18, they will not be able to complete this Holiday.
Caelise the Warlock: Unofficial Elder of '09 due to account-wide achievements. Secondary account does not currently have Legion, if new content is added in '18, they will not be able to complete this Holiday.
Ilgrid the Warrior: Unofficial Elder of '09 due to account-wide achievements. Current level is restricting the completion of Holiday content. Secondary account does not currently have Legion, if new content is added in '18, they will not be able to complete this Holiday.
Ruepart the Paladin: Unofficial Elder of '09 due to account-wide achievements. Current level is restricting the completion of Holiday content. Secondary account does not currently have Legion, if new content is added in '18, they will not be able to complete this Holiday.