Journey Into Mystery, Vol. 1 #108 (1964) 1st app. King Sindri

"At the Mercy of Loki, Prince of Evil!" / "Tales from Asgard: Trapped By the Trolls!"
At the Mercy of Loki, Prince of Evil! - Thor comes across the weakened form of Doctor Strange, and changing to Don Blake, saves his life. Strange says that if there is any way to repay him, he needs only to ask. Meanwhile, Loki sneaks out of Asgard, and assuming the form of an old man, goes to see Dr Don Blake. He pretends to trip and drop his cane, while stumbling into Blake causing him to drop his. He then picks up the cane and throws it out the window, and then reveals himself to be Loki. When Blake goes outside to look for it, it's gone. He goes to Strange to get help in finding it, and using his spirit form, locates it on a dock being used by two homeless men as a fishing rod. Strange's ghostlike form scares them off, and Blake recovers his cane. He then goes to find Loki and the kidnapped Jane Foster. Calling upon Strange's help again, Jane is rescued and Loki is captured and returned to Asgard once again.

Tales of Asgard: Trapped by the Trolls - An unscrupulous goblin king sends captives down as slaves to work for the underground trolls. Little does he realize that his latest captive carries a hammer.
Release Date: 1964