Neotrup's answer is correct due to the following rule (specifically, the second sentence highlighted below in bold). I have changed the "Accepted answer" to reflect this.

712.14a If a spell or ability puts a transforming double-faced card onto the battlefield “transformed” or “converted,” it enters the battlefield with its back face up. If a player is instructed to put a card that isn’t a transforming double-faced card onto the battlefield transformed or converted, that card stays in its current zone.

Sobrinho: Answers to your question has been up for a while. Since there don't seem to be any more follow-ups or corrections that need to be made, I marked one of them as the "Accepted answer" so this topic can move out of the list of unanswered questions. In the future you can take care of this yourself using the "Mark as Answer" button on the response that you feel is the most helpful answer to your question.

I try to avoid marking my own responses when I do this, but in this case it was the most complete option.

Season of the Witch's effect looks at creatures that could have been declared as attackers during the Declare Attackers step but weren't. The ruling you found means you won't be penalized for not taking any additional actions to enable a creature to attack if it is currently unable. For example: if you choose not to activate Tidewater Minion's first ability, then it can't attack, so Season of the Witch won't destroy it. However, an enchanted/equipped Novice Knight who doesn't attack will get destroyed, because it could have been declared as an attacker. Likewise for any Defender while Arcades, the Strategist is around.

KASTAWEI: An answer to your question has been up for a while. Since there don't seem to be any follow-ups or corrections that need to be made, I marked it as the "Accepted answer" so this topic can move out of the list of unanswered questions. In the future you can take care of this yourself using the "Mark as Answer" button on the response that you feel is the most helpful answer to your question.

xcontla: Since it's clear you got a satisfactory answer to your question and there don't seem to be any follow-ups or corrections that need to be made, I marked it as the "Accepted answer" so this topic can move out of the list of unanswered questions. In the future you can take care of this yourself using the "Mark as Answer" button on the response that you feel is the most helpful answer to your question.

I try to avoid marking my own responses when I do this but in this case it was the only option.

No, you won't have to sacrifice Ball Lightning to its own ability.

You don't have to stack the triggers in a special way to make this work. Teferi's Veil makes the creature phase out "at end of combat" but Ball Lightning's ability triggers "at the beginning of the end step". Because Ball Lightning is phased out by the time the turn gets to the end step, its ability won't trigger at all. Even if it was a situation with two simultaneous triggers that needed to be stacked in a specific order, if the "phase out" trigger resolves first then there's nothing around for you to sacrifice when the "sacrifice this" trigger resolves.

You don't need to have a reason.

The first item in that list, "whenever they have priority", allows players to activate mana abilities at any time they'd normally be able to take an action. The other items in that list give players special permission to also activate mana abilities at times they normally wouldn't be able to take an action (because they don't have priority at those times), but only if a mana payment is needed at that specific time.

Keep in mind that if you pass priority with unused mana still in your mana pool, you're supposed to let other players know how much mana is still in your pool.

No, you won't be able to play another land in that example. In the current rules, you determine whether or not you can play a land by comparing how many land plays the game currently says you have to how many you've already played this turn. If the Dryad is gone, you've already made a land play, and there isn't anything else giving you additional plays, then that's it.

Keep in mind that playing lands doesn't use the stack and the active player gets priority again after a spell resolving, so if you want to go land-Dryad-land or Dryad-land-land, there's no opportunity for an opponent to "respond" by killing your Dryad before you play your second land. If you do something else in-between the Dryad and that second land, however, then the opponent will be able to respond with something.

Some previous versions of the rules allowed you to specify which "drop" you were using as you played each land, but it allowed for unintuitive situations where a player could use the additional drop, blink the object that was giving it, and then use its additional drop again. It was an odd and somewhat complicated rules quirk that was smoothed out when the rules for land plays were revised to the current version.

Yes, it still triggers. The declare blockers step of combat only gets skipped if there were no creatures declared as attackers or put onto the battlefield attacking. Otherwise, it always happens, even if it is impossible for any blockers to be declared. If Master of Cruelties is attacking then there will definitely be a declare blockers step and its last ability will trigger if it doesn't get blocked.

Bblackboltt: An answer to your question has been up for a while. Since there don't seem to be any follow-ups or corrections that need to be made, I marked it as the "Accepted answer" so this topic can move out of the list of unanswered questions. In the future you can take care of this yourself using the "Mark as Answer" button on the response that you feel is the most helpful answer to your question.

danielgonmar: You need to use double square brackets around the card's name to make the link work - Nine Lives, Resourceful Defense

To answer your question, since Resourceful Defense only moves counters between things you control, the same player has to control both Nine Lives and the Defense in order to use the Defense to move counters off of Nine Lives. If they're controlled by different players, which might be the situation in the original question where things are being moved around with Harmless Offering, then it won't work.

Also, it's much better to post a new question as its own topic rather than respond to a very old one. With the way this site works, adding a new post to a Rules Q&A discussion doesn't move the topic to the top of the list. This topic is about 4 years old, so the only reason I was aware of your comment is because the site auto-subscribed me for notifications on this topic after I originally posted in it. If you had happened to post in a topic where the only people involved in the discussion were no longer active users then no one would have seen your question.

joaka: An answer to your question has been up for a while. Since there don't seem to be any follow-ups or corrections that need to be made, I marked it as the "Accepted answer" so this topic can move out of the list of unanswered questions. In the future you can take care of this yourself using the "Mark as Answer" button on the response that you feel is the most helpful answer to your question.