There are 13 types of yaochuupai, for 52 tiles total. Since you'll discard about 17 or 18 tiles in a normal round, this is pretty difficult to get.
It actually says there are 11 types, 44 tiles, but that is incorrect. 1 & 9 of pin, wan, sou + 4 winds + 3 sangenpai = 13 typesAll discards are yaochuupaiThe makeup of your hand doesn't matterHouteihaiIf you try chankan on a tile for which you are furiten, the chonbo takes precedence, so be careful.Example) Ton round 2, shaacha, dora is nanKanRonWait for 4-pin or 7-pin, but you have no yaku, so you can't agari normallyBy the way, haitei is also called haitei raoyue.HaiteihaiTsumo with 3-pin, the haiteihaiThe last one for this time is "nagashi mangan".
Usually you make yaku based on the contents of your hand, but this is a super-unique yaku that's based on certain conditions related to your discards.
The conditions are:
・All of your discards are yaochuupai
・The round ends in a draw
・None of your discards were called
However, having called other players' tiles is no problem.Next is "chankan".
This is a yaku where you agari off of another player's kakan, and is the only way you can ron a tile other than a discard.
It's not something you can aim to get; it's a chance yaku that you'll hardly ever see.
The requirement is a kakan so you can't do it to another player's ankan.
However, kokushi musou is the one exception where you can get chankan on an ankan.
It takes places before the kan is completed, so another dora is not added, but this also means that if you get chankan within the limit for ippatsu, you can combine the two.
This is another circumstantial yaku, so it's possible to agari with it even if you have no other yaku.This is an agari via ron on your kamicha's 4-pin, so it's "chankan, 2 dora"
The agari with chankan occurs before the kakan is completed, so a new dora is not added.Next up are "haitei mouyue" and "houtei raoyui".
Haitei mouyue is a yaku you get when you tsumo agari from the last tile in the wall, and houtei raoyui is a yaku where you ron the last tile discarded into the river.
Ther are rules that "you cannot ankan or kakan the haiteihai (last drawn tile)" and "no fuuro on the houteihai (last discarded tile)", so neither haitei nor houtei can be combined with rinshan kaihou or chankan.
However, if you win by drawing the last tile one turn after declaring riichi, you'll get riichi ippatsu haitei tsumo.Ron on 1-wan, the houteihaiDrawIt's uncool to get hit with a houtei ron because you were aiming for keiten (tenpai with no yaku), so watch out.
