インスタント
クリーチャー1体を対象とする。ターン終了時まで、それは+1/+0の修整を受けるとともに破壊不能を得る。(ダメージや「破壊」と書かれた効果では、それは破壊されない。)
調査を行う。(「

, このアーティファクトを生け贄に捧げる:カードを1枚引く。」を持つ無色の手掛かり・アーティファクト・トークンを1つ戦場に出す。)
You can't cast a spell without choosing legal targets. If all of those targets become illegal, the spell doesn't resolve and you won't investigate.
Clue is an artifact type. Even though it appears on some cards with other permanent types, it's never a creature type, a land type, or anything but an artifact type.
You can't sacrifice a Clue to pay multiple costs. For example, you can't sacrifice a Clue token to activate its own ability and also to activate Alquist Proft, Master Sleuth's ability.
If an effect refers to a Clue, it means any Clue artifact, not just a Clue artifact token. For example, you can sacrifice Wrench to pay for Alquist Proft, Master Sleuth's activated ability.