For Android or iOS users what is your favorite online multiplayer word game and why

My current favorite is Word Battle.
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​It's free to play, but you need a Facebook account. I think it's been on Facebook for a long time, but I never play Facebook games so I didn't know about it.
I love this game because it's fun, challenging, four-player, and there are many skilled players. Best of all, there's no waiting on opponents. You play same time start to finish. I love Scrabble and Words With Friends, but I rarely play them because I hate waiting for moves.
(Note to any app developers: there is no online 'Scrabble-like' game that forces players to play in real-time, start to finish, like it should be. Fill a void and make some skrilla. I'm sold.)
Each match consists of four rounds for up to four players. You build words from the same letters to score points. Letter values work like Scrabble, except sometimes extra value or multipliers are added to individual tiles.
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​If you're tied with points after four rounds, the match winner is most tiles played. If your tile amount is tied, the quickest player wins.
This makes the battles a lot of fun as you try to anagram the highest point value in as little time as possible. You can see your opponent's tiles as they place them, but not the letters. When you're playing three other players with similar skill, the battles get quite intense.
You'll want to make a play in the first 5-10 seconds, and spend the rest of the round trying to top it. It's a great feeling finding an eight-letter top scoring word in five seconds. Quick fingers will help.
There are three power ups to make things more interesting: validate, +20 seconds, and add a random letter. The last one can really change the game in the last ten seconds.
The power ups cost coins. You earn coins with daily logins or winning tournaments. You can buy them too, but not through the app. When you click the 'add coins' icon you're told that currently you can only make purchases on the Facebook website.
​​Been like this since I found the game on Google Play. Seems silly they spent all that time porting the game, but stopped short of coding it to earn a buck or two. The coins are reasonably priced so there's money to be had. My money at least.
Also, the game allows you to chat to players between matches, but again, only on your PC or Mac. It seems they rushed the port to mobile; a bit ironic as the game is much more suited to touchscreen devices versus a mouse and keyboard.