I'm just curious about the paragraph under "Upkeep Phase". It says that you always choose the order in which events affect your creatures. But then it goes on to say "In the rare case that a timing issue occurs, the player with the initiative decides the order." Now it seems to me the example following that with the Highland Unicorn would be a prime example of a "rare timing issue", would that indeed be the case? Can you provide a better example of a timing issue that would go to the initiative player for decision?
I think the rules are clear that in the example with the Highland Unicorn, the controller of the unicorn decides whether to Regenerate or resolve the Burn first. In order for there to be timing issues that are not resolved by this ruling, the timing probably needs to affect multiple players' creatures.
Here's an example I could imagine: Suppose the Warlock was suffering from Ghoul Rot and could die from it this Upkeep. But the Warlock had also enchanted a wounded Blue Gremlin which is suffering from Burn with Death Link. If the Gremlin dies to the burn before the Warlock can heal himself with Death Link, the Warlock dies to Ghoul Rot. But if the Warlock can use the Death Link first, then he would survive another round. You could perhaps argue that both Death Link and the Burn affect the Gremlin, so the controller of the Gremlin gets to decide the order. But from another point of view, Death Link and Ghoul Rot both affect the Warlock, so the Warlock decides the order there. Then the question becomes do we resolve the Gremlin or the Warlock first? This should probably be decided by the player with initiative.
I invented this example out of whole cloth. Perhaps someone has an example that came up in play?