Rule 359.3.e.12

If the spell checks information about a target that is no longer legal or a card or permanent whose location, zone, or status has changed such that that information is no longer available, that check returns "null" and all calculations based on it are ignored. Examples: A unit that is no longer on the board is treated as having null Might, null cost, etc. A unit that is no longer on the board has no location, is neither exhausted nor readied, etc. Baited Hook says "[1][C], [E]: Kill a friendly unit. Look at the top 5 cards of your Main Deck. You may banish a unit from among them that has Might up to 1 more than the killed unit and play it, ignoring its cost. Then recycle the rest." While Baited Hook’s ability is on the chain, an opponent reacts with a spell that returns the friendly unit to its owner's hand. Because the friendly unit is no longer a legal target, it can't be killed and its Might is treated as null. Baited Hook’s controller looks at the top 5 cards of their Main Deck, but can’t choose any unit from among them. Strike Down reads “Choose an equipped friendly unit. It deals damage equal to its Might to an enemy unit. Then detach an Equipment from it.” While Strike Down is on the chain targeting a unit with only one Equipment attached to it, that unit has its Equipment detached via Angle Shot. When Strike Down goes to resolve, the targeted unit is no longer legal, so the unit’s Might will return as “null” and the instructions related to it are ignored.