Targeting

What makes something a target?Copy Anchor Link

Unless one of the exceptions below applies, a game object, player, or zone mentioned by a spell, activated ability, or triggered ability is a target.^[355.10] Card text does not need to say "target" or "choose"; for example, "Kill a unit" targets a unit.^[355.9.a]

The only exceptions are:

• Selections made with "pick": A game object, player, or zone that a card tells a player to pick is not a target.^[355.7]
• Counters: A counter is not targeted by spells or abilities.^[742.1] If an effect instructs a player to interact with a counter, that counter is chosen when the instruction executes.^[742.1]
• Objects in non-public zones: An object in a non-public zone is not a target.^[355.10.a] For example, "You may play a unit from your hand" does not target a card in hand.
• Restrictions or permissions for another choice or action: Something mentioned only as a targeting restriction, or as a restriction or permission for another game action, is not a target.^[355.10.b] "Kill a unit at a battlefield" targets the unit but not the battlefield, while "Play a unit from your hand to a battlefield" does not target the battlefield.
• Objects used only in costs, trigger conditions, or replacement effects: Something included only as part of a cost, trigger condition, or replacement effect is not a target.^{[355.10.c][355.10.c.1]} The dying unit in "When a friendly unit dies, kill a gear" is not a target, but the gear is.
• Objects determined without a choice: An object identified from its characteristics without that controller choosing it is not a target when no choice is ever possible.^{[355.10.d][355.10.d.1]} In "Kill all units at a battlefield," the units are not targets, but the battlefield is. An instruction to "Kill a unit at a battlefield" still targets a unit when only one is legal.^[355.10.d.2]
• Sets chosen by other players: An object in a set chosen wholly or partly by other players is not a target.^[355.10.e] "Each player kills a unit they control" targets nothing.
• Objects identified by "must" instructions: An object identified by that instruction is not a target, even if the player chooses which object satisfies it.^[355.10.f] "You must recycle one of your runes" does not target, while "Recycle a rune you control" does.
• Legends you control: A legend identified as one "you" control is not a target; if you control multiple legends, you choose one when the spell or ability resolves.^[355.10.g]

Does "Kill a unit if it has 3 might or less" mean I can only choose a unit with 3 might or less?Copy Anchor Link

No; you can choose any otherwise legal unit, and the might condition controls only whether the kill instruction is performed.

Targeting restrictions describe the target, as in "Kill a unit with 3 might or less."^[355.9.b] In "Kill a unit if it has 3 might or less," the later "if" condition is instead part of the effect executed when the spell or ability resolves.^{[359.3.d][407.5]}

What happens if a target becomes illegal before a spell or ability resolves?Copy Anchor Link

The spell or ability still resolves, but the illegal target is unaffected, instructions related to it cannot be followed, and independent instructions continue normally.^{[359.3.e.1][359.3.e.5][407.5]}

If all of an instruction's targets are illegal, that instruction does not execute.^[359.3.e.7] If at least one target remains legal, the instruction executes using only the legal targets.^[359.3.e.8] If a group of targets no longer collectively meets its targeting restriction, the spell or ability's controller must choose a legal subset of the original targets for it to affect.^[355.11.b] The subset must include the maximum number of legal targets possible for that subset.^[355.11.b.1]

A target is illegal when the spell or ability resolves if it no longer meets the targeting requirements or has changed zones to or from a non-board zone.^[359.3.e.2] A target that stops meeting a requirement and then meets it again is legal, but a target that changes to or from a non-board zone is a new object and remains illegal even if it returns.^{[359.3.e.3][359.3.e.4]}

If an instruction needs information from the illegal target, that information is null and all instructions based on it are ignored.^[359.3.e.12] If a later instruction is linked to an earlier instruction that was ignored, the later instruction is also ignored.^{[359.3.e.14.a]}

What is the difference between an ignored and a negated instruction?Copy Anchor Link

An instruction that can't be followed because of an illegal target or unavailable information is ignored; an instruction that can't be followed for any other reason is negated.^[359.3.e.6] Mistargeting means that a chosen target is illegal or unavailable when the instruction executes.^[359.3.e.9]

The distinction controls later linked instructions. If an earlier linked instruction is ignored, its later linked instructions are also ignored.^{[359.3.e.14.a]} If an earlier linked instruction is negated, later linked instructions continue unless they directly reference the negated game action.^{[359.3.e.14.b]}