If you do not control the Abandoned Hall, nor have any units present, and you activate "Ride the Wind" to move a unit to the Abandoned Hall, are you still allowed to trigger the Abandoned Hall to gain +1 might as a spell was played?

Yes, you are allowed to trigger the Abandoned Hall ability to give your unit +1 [M] (Might) in this scenario.

According to RiftJudge FAQ #11036 and the authoritative interpretation regarding Abandoned Hall (which supersedes earlier, conflicting FAQs), the "When a player plays a spell" ability triggers after the spell has successfully completed its resolution process.

Sequence of Events

1. Play Spell: You play Ride the Wind as an [Action]. It is placed on the chain.
2. Resolution: Ride the Wind resolves. Its effect executes: your target unit is moved to the Abandoned Hall and readied.
3. Trigger Condition Met: Because Ride the Wind has successfully completed its resolution, the "When a player plays a spell" condition on Abandoned Hall is fulfilled.
4. Trigger Placed: The Abandoned Hall ability is placed on the chain.
   • Note on Control: As established in the Rules FAQ Clarification 2026-04-29, the player making the choices for a triggered ability of a battlefield (you, in this case, by choosing to resolve the "may" ability) controls that ability and is responsible for adding it to the chain.
5. Resolution: You resolve the Abandoned Hall trigger. Because your unit was moved to the Abandoned Hall during the resolution of Ride the Wind (which occurred before this trigger was placed on the chain), it is currently at the Abandoned Hall and is a legal target to receive the +1 [M] buff.

Key Clarifications:

• Trigger Timing: Triggered abilities that occur when a card is played (such as the one on Abandoned Hall) are placed on the chain only after the spell's resolution process is fully complete.
• Targeting: Because the unit arrives at the battlefield before the Abandoned Hall trigger is placed on the chain, it is present on the board when the trigger resolves and is therefore a valid target for the buff.
• Control: The fact that you did not control the Abandoned Hall prior to playing the spell does not prevent you from using its triggered ability; by choosing to use the "may" ability, you take control of that instance of the ability.