クリーチャー — 人間・ならず者
2 / 1
あなたが手掛かりを1つ生け贄に捧げたとき、果敢な捜索者を変身させる。
クリーチャー ― - 人間・ウィザード
3 / 2
果敢(あなたがクリーチャーでない呪文を1つ唱えるたび、ターン終了時まで、このクリーチャーは+1/+1の修整を受ける。)
禁断の真相を知る者がプレイヤー1人に戦闘ダメージを与えるたび、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。)
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.
If Daring Sleuth's ability triggers multiple times before any of those abilities resolves, only the first one to resolve will cause it to transform.
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.
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.