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.
Hidden Reserves
Battle: If there are any enemy units at the current battlefield: Attach this card from your hand to your target personality at any location. Move him to the current battlefield.
My question: When you use the battle action and attach the card do you have to pay the gold cost? Normal templating I have seen for other cards would say "attach (paying all costs)" so I am confused
Many thanks
When you use the battle action and attach the card do you have to pay the gold cost?
Yes, when you bring a card into play, you must pay all required costs such as its Gold cost, unless an effect reduces or waives those costs.
Physically marked card states, In play and out of play: "For a card to enter play, its conditions and requirements of play must first be met, and its costs of entering play must then be paid."
See also Card types, Attachments, Using attachments.
Normal templating I have seen for other cards would say "attach (paying all costs)"
This was a reminder text that you would no longer see on new cards. Now players are assumed to know that bringing a card into play (e.g. by attaching it) normally requires to pay all costs.