• At (one's) peril
• At (someone's) best
• At (someone's) bidding
• At (someone's) breaking point
• At (someone's) command
• At (someone's) convenience
• At (someone's) discretion
• At (someone's) disposal
• At (someone's) earliest convenience
• At (someone's) elbow
• At (someone's) expense
• At (someone's) fingertips
• At (someone's) heels
• At (someone's) leisure
• At (someone's) peak
• At (someone's) service
• At (someone's) wit's end
• At (someone's) wits' end
• At (someone's) worst
• At (someone’s) disposal