Getting to cascade Questing Beast into Sanctum Prelate to protect it sounds wonderful
But we're talking a 6-mana chunker with no protection of its own, so if you want this to pan out, you need to have scry sources in play immediately upon resolution, or have a plan for getting Eligeth to stick
You get tons of control over what you sacrifice, from the tokens produced by Jadar, Ghoulcaller of Nephalia to cards like Heaped Harvest and Ichor Wellspring that encourage you to remove them
However, this weakness can be overcome by using cards that force the "Timelord" monster to be attacked
PSA have an article here that will explain the benefits of having your cards graded in certain situations that can help you decide whether to get your cards graded and how it could be of benefit to you based on various different circumstances
[Main] Place this Tamer as any of your [Mother Eater]s' bottom digivolution card