Blessed Alliance

• WWizards of the Coast2016-07-13
  Official Ruling
  If one target of an escalate spell becomes illegal, the other targets will still be affected. If all of the targets become illegal, the spell won’t resolve.
• WWizards of the Coast2016-07-13
  Official Ruling
  You can’t choose any one mode multiple times.
• WWizards of the Coast2016-07-13
  Official Ruling
  Additional costs don’t affect a spell’s mana value.
• WWizards of the Coast2016-07-13
  Official Ruling
  You choose all of your modes at once. You can’t wait to perform one mode’s actions and then decide to choose more modes.
• WWizards of the Coast2016-07-13
  Official Ruling
  Effects that reduce the cost of spells reduce the total cost, including any escalate costs added.
• WWizards of the Coast2016-07-13
  Official Ruling
  Untapping an attacking creature doesn’t cause it to be removed from combat.
• WWizards of the Coast2016-07-13
  Official Ruling
  If two of the chosen modes of an escalate spell target a creature, you may choose the same creature for each mode’s target, or choose different creatures. The same is true if the chosen modes target a player (or opponent).
• WWizards of the Coast2016-07-13
  Official Ruling
  The targeted opponent chooses which of their attacking creatures to sacrifice, not you.
• WWizards of the Coast2016-07-13
  Official Ruling
  If an effect allows you to cast a spell that has escalate without paying its mana cost, you pay escalate costs for that spell if you choose more than one mode.

Rulings via Scryfall