A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 10 February 2012
I've noticed two things about At Any Cost.
1. It has Will as a keyword.
2. It is nearly the same as Will, the differences being that the two gold cost reduction is not printed on the card (it is now supposedly in the rules [see below] that a personality who belongs to your clan can be brought into play for two less gold regardless of when they're being brought into play) and the cost of the card itself is 0, while you still have to "pay all costs" of the personality. (It also no longer requires opposition or ignores honor requirements, though ignoring honor requirements can be done at any time for in-clan personalities.) Effectively speaking, this makes it a slightly tweaked copy of Will, which has been given wording that fits with the EE rules. (I think no more difference than that between the Samurai version and the CE version.)
Does this mean that At Any Cost is actually an MRP'd Will, and old copies of Will can thus be played in EE using the updated wording? (It sure seems to me that it should be so. I don't want to spend $15 each on a card just because the words "honor requirement" and "opposed" have been left off when I already own three!)
"Clan Discount and Ignoring Honor Requirements Now all rules for bringing people into play, except Proclaim, apply at all times, meaning you can apply your clan discount and pay extra gold to ignore honor requirements any time you bring someone of your clan into play. This change was made to simply be more intuitive." (http://www.l5r.com/news/emperor-edition-design-diaries-new-rules/)
(The EE Comprehensive Rules seem unclear/contradictory on this matter, saying "if it's the player's dynasty phase" under "Playing Personalities" and then "before each time a player brings a personality into play" [with an obvious lack of stipulations] under "Clan Alignment and Entering Play".) http://rules.l5r.com/EE_Card_types#Personalities
Jon Palmer (rules official), 11 February 2012
I've noticed two things about At Any Cost.
1. It has Will as a keyword.
2. It is nearly the same as Will, the differences being that the two gold cost reduction is not printed on the card (it is now supposedly in the rules [see below] that a personality who belongs to your clan can be brought into play for two less gold regardless of when they're being brought into play) and the cost of the card itself is 0, while you still have to "pay all costs" of the personality. (It also no longer requires opposition or ignores honor requirements, though ignoring honor requirements can be done at any time for in-clan personalities.) Effectively speaking, this makes it a slightly tweaked copy of Will, which has been given wording that fits with the EE rules. (I think no more difference than that between the Samurai version and the CE version.)
Does this mean that At Any Cost is actually an MRP'd Will, and old copies of Will can thus be played in EE using the updated wording? (It sure seems to me that it should be so. I don't want to spend $15 each on a card just because the words "honor requirement" and "opposed" have been left off when I already own three!)
"Clan Discount and Ignoring Honor Requirements Now all rules for bringing people into play, except Proclaim, apply at all times, meaning you can apply your clan discount and pay extra gold to ignore honor requirements any time you bring someone of your clan into play. This change was made to simply be more intuitive." (http://www.l5r.com/news/emperor-edition-design-diaries-new-rules/)
(The EE Comprehensive Rules seem unclear/contradictory on this matter, saying "if it's the player's dynasty phase" under "Playing Personalities" and then "before each time a player brings a personality into play" [with an obvious lack of stipulations] under "Clan Alignment and Entering Play".) http://rules.l5r.com/EE_Card_types#Personalities
At Any Cost and Will are completely separate cards. This was done for several cards in Emperor Edition (Beloved of the Clan vs Rumors Travel, for instance), and the cards are not mechanically the same so new cards were created. At Any Cost has the "Will" keyword but in no other way is related to the card Will; you may play 3 of each in Legacy.
As for Clan Discount and Clan Allegiance, the second part is correct. I'll talk with Roger about cleaning up the text due to the confusion, thank you for pointing it out.