I say it IS possible. Not sure though. This is how I think it would happen:
1.G.Vassal+Secret Pass
2.Summon your high atk monster(ie BEUD)
3.Activate U.A.(I think the calculation takes place before the BattlePhase)
4.Activate GotM(GVassal gains the other monster's atk)
5.Enter BattlePhase(GV gains the sum.It doesn't matter if BEUD is not on the field. The sum was calculated before you tributed it)
Nope. I tried with that combo. The description in Union Attack clearly says that during the battle phase, the selected monster will gain the attack, if its the only card on your side of the field, nothing will happen.
I think the answer is no.
But what if you change Gift of the Martyr to Spell Reclamation?
Remember to set Spell Reclamation on the field.
In the last turn.
1.G.Vassal+Secret Pass
2.Summon your high atk monster(ie BEUD or Master of OZ)
3.Activate U.A. and use Spell Reclamation.
4.You get U.A back, use it the second times.
5. Attack.
No, if you use them together, you will not use full potential of both cards. Union Attack will combine all ATK of face-up monsters you control at the START OF THE BATTLE PHASE. For example, you control Vassal, and 2 BEWD. In the main phase you apply Union Attack on Vassal(it will not calculate the ATK for now) , then sacrify one BEUD using Gift of the Martyr, your vassal become 3700.
After that, you get to the battle phase. Now the Union Attack will sum all ATK of monsters you control, which is one vassal (3700) and one BEWD (3000). The resultant ATK is only 6700. Now you see how if you use only one Union Attack and no Gift of the Martyr. You don't sacrify any monster, so you have one Vassal and 2 BEWD.
At the start of the battle phase, Union Attack sums all ATK; Vassal (700) + BEWD (3000) + BEWD (3000) = 6700. You see, using one Union Attack gives the same result as using two cards (Gift of the Martyr + Union Attack).
For my suggession
1. Same as Moon says, if you want to use Union Attack, replace Gift of the Martyr with Spell Reclamation or 2nd Union Attack if you have.
2. If you want to use Gift of the Martyr, forget Union Attack and Vassal and go for Piranha or Cu Chulainn instead.
Nicholas
Anoymous
