Basic combo: 3,2, basic attacks.
Basic attack combo: 3, basic attack, 2, basic attacks.
Ice Wall combo: 3,1 (behind the target), 2, basic attacks.
Ultimate combo: 3, 2, 4 (you can use basic attacks between the skills).
Blink Rune combo: You can start one of the previous combos with Blink Rune.
Mix them: You can combine these combos the way you like.
Anyway, I've downvoted this guide because it's terrible. Sure Ymir can put out the damage, but without some protections, you're looking at possibly having double digit deaths.
And I just updated the title of the guide, but the build title, was always the same (Joust Build (Full dmg)).
I already edited the guide title, but it doesn't change.
Not a good build.
I've been playing with it, and is very easy to get triple kills (in joust mode). Is just a different way to play Ymir, instead of a tank, I understand if you don't want to test it.