DND_Reborn
The High Aldwin
The key issue Arial Black and other supporting that position have is this: because the Attack action and bonus action shove can be simultaneous, only the order of resolving them needs to be determined. He stated this ordering is determined by the player, which is slightly incorrect as it is the DM who controls the narrative, but since the DM often defers to the player's wishes, this is a very minor oversight really.
The problem with even allowing the shove to be resolved first, assuming the Attack action is simultaneous but the DM allows it to be resolved second, is scenarios where after you resolve the shove you cannot attack anything and thus never take the Attack action. If you never take the Attack action, you never satisfied the condition of Shield Master which allowed you to shove. This leads to paradox and how do you handle that?
Example. You party has been engaged in a battle with an archmage. Everyone else is unconscious or dead, so it is just you and him now. On your turn, you employ your bonus action to shove, deciding to resolve it before resolving your attack from your Attack action. Unknown to you, the archmage's contingency was if he is knocked prone by an enemy, he teleports to his hideout. So, the DM says as soon as you knock the archmage prone, he disappears. But, you have no target to attack with your Attack action, so how can you take it on your turn???
Now, you might argue that since your actions were simultaneous, you should be able to resolve your attack before he teleports away. The DM agrees, thinking this will avoid the paradox, so you make your attack roll and do so with advantage (after all, you shoved the target, right?). The DM puts his hand up before you roll, telling you that you don't have advantage because the actions are simultaneous, since even though he is allowing you to resolve one and then the other you agreed they occur at the same time. So, since they are simultaneous you cannot benefit from the effect gained by shove until the simultaneous actions are both resolved. If you argue against this, you are not in fact doing the actions simultaneously. If you try to benefit from the prone target via Shield Master, it in fact came first and the attack followed second. If one is first and the other is second, they aren't simultaneous.
The DM could tell you to roll two d20's at the same time since the actions are simultaneous. One d20 is for the Strength (Athletics) check versus the archmage's Dexterity (Acrobatics) check for the shove, and the other d20 is for your attack roll versus his AC. Since they happen together, you don't have advantage on the attack roll.
If you claim they are simultaneous, the order of resolution is not important because you cannot benefit from the shove (advantage on attack) since the opponent is not prone when you simultaneously make the attack roll. At best, you could resolve it as "shove, attack (no advantage because the shove is simultaneous), attack (with advantage since the shove is now complete)". This is no different from "attack, shove, attack (with advantage due to shove)". In short, it is easier to resolve the order as: "attack (no advantage), shove, attack (with advantage)", since this makes it more obvious when you can attack with advantage than resolving them as "shove, attack (no advantage), attack (with advantage)". You have the exact same actions with the exact same benefits, only the order changes between the shove and first attack.
This is actually pretty important in another way if you think about this: suppose you only have one attack for your Attack action (no Extra Attack)?
By the argument of simultaneous actions, that the shove and attack must occur together, you can never gain the benefit from the prone target because the actions are simultaneous! It becomes irrelevant if you shove then attack or attack and then shove when the actions are simultaneous.
I hope at this point no one is still arguing you can use the bonus action and THEN use the Attack action, that they need not be simultaneous or that the Attack action must come first. The only two logical interpretations IMO are:
1. The bonus action Shove can be taken simultaneously to the Attack action.
2. The bonus action Shove must be taken after the Attack action.
Either way, unless you have the Extra Attack feature, you can never benefit from the shove on the first attack made on your turn. Of course, as I have shown in other posts, this goes against JC's official stance from SA and tweets, but that is only of concern to your table if you value his position.
The problem with even allowing the shove to be resolved first, assuming the Attack action is simultaneous but the DM allows it to be resolved second, is scenarios where after you resolve the shove you cannot attack anything and thus never take the Attack action. If you never take the Attack action, you never satisfied the condition of Shield Master which allowed you to shove. This leads to paradox and how do you handle that?
Example. You party has been engaged in a battle with an archmage. Everyone else is unconscious or dead, so it is just you and him now. On your turn, you employ your bonus action to shove, deciding to resolve it before resolving your attack from your Attack action. Unknown to you, the archmage's contingency was if he is knocked prone by an enemy, he teleports to his hideout. So, the DM says as soon as you knock the archmage prone, he disappears. But, you have no target to attack with your Attack action, so how can you take it on your turn???
Now, you might argue that since your actions were simultaneous, you should be able to resolve your attack before he teleports away. The DM agrees, thinking this will avoid the paradox, so you make your attack roll and do so with advantage (after all, you shoved the target, right?). The DM puts his hand up before you roll, telling you that you don't have advantage because the actions are simultaneous, since even though he is allowing you to resolve one and then the other you agreed they occur at the same time. So, since they are simultaneous you cannot benefit from the effect gained by shove until the simultaneous actions are both resolved. If you argue against this, you are not in fact doing the actions simultaneously. If you try to benefit from the prone target via Shield Master, it in fact came first and the attack followed second. If one is first and the other is second, they aren't simultaneous.
The DM could tell you to roll two d20's at the same time since the actions are simultaneous. One d20 is for the Strength (Athletics) check versus the archmage's Dexterity (Acrobatics) check for the shove, and the other d20 is for your attack roll versus his AC. Since they happen together, you don't have advantage on the attack roll.
If you claim they are simultaneous, the order of resolution is not important because you cannot benefit from the shove (advantage on attack) since the opponent is not prone when you simultaneously make the attack roll. At best, you could resolve it as "shove, attack (no advantage because the shove is simultaneous), attack (with advantage since the shove is now complete)". This is no different from "attack, shove, attack (with advantage due to shove)". In short, it is easier to resolve the order as: "attack (no advantage), shove, attack (with advantage)", since this makes it more obvious when you can attack with advantage than resolving them as "shove, attack (no advantage), attack (with advantage)". You have the exact same actions with the exact same benefits, only the order changes between the shove and first attack.
This is actually pretty important in another way if you think about this: suppose you only have one attack for your Attack action (no Extra Attack)?
By the argument of simultaneous actions, that the shove and attack must occur together, you can never gain the benefit from the prone target because the actions are simultaneous! It becomes irrelevant if you shove then attack or attack and then shove when the actions are simultaneous.
I hope at this point no one is still arguing you can use the bonus action and THEN use the Attack action, that they need not be simultaneous or that the Attack action must come first. The only two logical interpretations IMO are:
1. The bonus action Shove can be taken simultaneously to the Attack action.
2. The bonus action Shove must be taken after the Attack action.
Either way, unless you have the Extra Attack feature, you can never benefit from the shove on the first attack made on your turn. Of course, as I have shown in other posts, this goes against JC's official stance from SA and tweets, but that is only of concern to your table if you value his position.