semi bluff in a blind battle & river play when board pairs

[jt1]

Villian is loose with unknown aggression

Party Poker 3/6 Hold'em (6 max, 3 handed) converter

Preflop: Hero is BB with J[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/heart.gif[/img].
<font color="#CC3333">Button raises</font>, <font color="#666666">1 fold</font>, Hero calls.

Flop: (4.33 SB) A[img]/images/graemlins/diamond.gif[/img], 7[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets</font>, <font color="#CC3333">Hero raises</font>, Button calls.

Turn: (4.16 BB) J[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, Button calls.

River: (5.66 BB) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>

Hero's play?