How to calculate ACB for Syndicates

I am not sure how to handle taxes on syndicates where coin is sold at 50% off.

I’m in Canada, so a trade is considered a disposition (taxable) of the sell coin at fair market value and the acquisition of the buy coin.

When I am then calculating the adjusted cost basis of the syndicate coin (at 50% discount), should I be using the fair market value (whatever the coin is trading at) or the fair market value of a coin at 50% discount?

I’m curious to know how folks in other systems that use adjusted cost basis calculate their cost for the Syndicate altcoins.