> In [4], the author presents a Magic: The Gathering end- game that embeds a universal Turing machine. However, this work has a major issue: it’s not quite dete

> In [4], the author presents a Magic: The Gathering end- game that embeds a universal Turing machine. However, this work has a major issue: it’s not quite deterministic. At several points in the simulation, players have the ability to stop the computation at any time by opting to decline to use effects that say “may.” For example, Kazuul Warlord reads “Whenever Kazuul Warlord or another Ally enters the battlefield under your control, you may put a +1/ + 1 counter on each Ally you control.” Declining to use this ability will interfere with the Turing machine, either causing it to stop or causing it to perform a different calculation from the one intended. The construction as given in Churchill [4] works under the assumption that all players that are given the option to do something actually do it, but as the author notes it fails without this assumption. Attempts to correct this issue are discussed in Churchill et al. [5]. In this work, we solve this problem by reformulating the construction to exclusively use cards with mandatory effects So they only use cards with mandatory effects/triggers. Doesn't this mean that this whole work if flawed because it only applies to a subset of MTG cards?