-을 테니

Used to state your own intention and then ask or suggest something.

Rule: After a stem ending in a consonant, use -을 테니 (먹을 테니). After a vowel or ㄹ, drop the 을 (갈 테니). The first clause is what the speaker will do, so the subject is normally 'I'. -을 테니까 is the more conversational form.