HP Attack Manipulation

So, I was playing offline with one of my friends the other day with Sil'fer, who had a Sange Yasha equipped. I decided to use HP Attack with it because it has 10 hp, so it would be pretty strong. Little did I know that when I did this, its current HP was set to 4, Drain triggered to gain 4 or 5 hp, and then the hp and ap switched back and I had somewhere around 8 ap this time.
I found this to be ridiculous, so I made a rather successful deck with it. All you really need is 3 Sange Yashas and 3 HP Attacks. I also use Ravanas and Grow Guards (which works great against stupid offline enemies, but online you could use the Grow Guards on the Sange Yashas), and you can use Mags or Barriers to fill in the extra 1-cost space. Since this only allows you to attack once, I would include Round Slays or other attacks with good multi range. I typically deal at least 15 damage per attack, and that allows you to gain 5 hp for your Sange Yasha. Overall, this is a rather consistent strategy (I almost always get A's or S's offline) that can both deal and recover large amounts of damage.

If you have any suggestions for making it useful, they would be appreciated, but keep in mind I am only CLVL 57 (sadly), so I don't have all that much yet.

Its been a while since I've used a that sort of Sange yasha setup. I can't think of any obvious weaknesses besides the usuall " watch out for companion and counter cards."

no doubt this is 1 of my favorite offline decks to use as well, i like to pair it with kaladbolg though so i got a second wep to attack with to draw out def or whatever and it has ac disrupter which is very useful to shut down tech using coms which get annoying in offline mode since tech defense cards like patience are 3 cost where online only costs 2 and avert also costs 2 offline where onkline it was only 1 cost. using this deck online though especially vs ppl you need to change up ur strategy a bit like this guy above me said companion and counter cards are commonly used amongst real players and also online this card is given a blue bar at the top so blue bar defense cards like cancel completely shut hp attack down. great deck to use offline not much to it vs coms, heavy slashes, round slays, n stabs n ur set maybe a right heavy punch. online vs ppl ud wanna add things like maybe lock on 3 cards to shut down companions and counter and your gonna find cancel becomes a very annoying def card to shut this down, another one not commonly used by coms ur gonna hate is tp defense. offline itsa great deck. online it can be as well but is a bit riskier and requires alot of tweeks.

you could also try using drain + HP attack ;)
i love using it with a spread needle.. it's a bit of a high-cost deck, but a spread needle with 10 or more ATP is damn effective!

Sange & Yasha already has drain built in. Does that ability stack when you use the action card Drain?

Once you get Sange & Yasha's AP up high, the drain ability allows for a bit more wiggle room to use chance based defense cards. With 10 HP you can afford to use Companion, Counter(+) and SP Counter because drain (with 10AP behind it) gets you back a good number of hitpoints if needed.
Practical uses of those cards are limited; Companion and Counter would help to clear a path against spamming Arkz players. But using Counter cards can be good fun.

As a sidenote, I never knew the American version of this game has a different version of Patience. On my disc (offline) it costs 2 points to use, it also shows it costs 2, and it has +5HP. If memory serves that was the same as online.
Are there any other cards that are different between the separate regions?

no drain effects do not stack. and many cards had different stats online. after the last card evolution they did, avert was 1 cost online, dice plus is 3 cost, penetrate guard 1 cost +1 hp, cross scar 3ap 4 tp, st rappy was given gimped hp and i think lost a point of ap too, red slimes hp and iirc ap and tp was also gimped. there was tons of changes online. brionac was only 1 cost online, theres more cant think of em all atm. but ya i dont believe this was a regional change, i believe it was just an offline vs online stat change.