When this pattern is used in the 1st person with an action verb, it indicates reason or cause of the speaker's plan or intention.

- is used with action verbs
- is a compound of -ㄹ(을) 터이다 and -(으)니까
- is usually followed by a command, question, or suggestion
- the final 니까 is optional
- 을 테니까 attaches to verbs ending in a consonant
- ㄹ 테니까 attaches to verbs ending in a vowel
- in some contexts, when used with a 3rd person subject, it can show the speaker's conjecture or supposition. When used like this, it can be used with any verb.

Examples:
잘 대접할 테니까, 꼭 오세요./I'll treat you well, so come for sure.
도와 드릴 테니, 같이 갑시다./I'll help, so let's go together.
하사님이 분주할 테니, 방해하지 마세요./I think the sergeant is very busy, so please don't disturb him.