I noticed the Boar's Charge ragepower
While raging, when you hit with a gore attack as part of a charge, you automatically score a critical threat. You must still confirm the critical hit as normal.
I figured it was neat, but couldn't be broken because it would be limited to one attack a round. I wanted to capitalize on it though and looked for ways to get gore attacks. Then I found the Beatstrike Club
When transformed, the club counts as a natural weapon and a manufactured weapon for the purpose of spells and effects that enhance or improve either manufactured or natural weapons.
The club also counts as the natural weapon of its current shape for the purpose of feats and spells that rely on specific natural weapons, such as Weapon Focus (bite) or the bloody claws spell.
It's a manufactured weapon (you can full attack with it) that triggers feats (so just pick up Boar's Charge with Extra Rage Power) that improve gore. Take Disemboweling Tusks and then every hit does 1d4 con damage if it confirms a critical hit.
TWF with these for up to 3 extra attacks. After haste and a real/Helm of the Mammoth Lord gore attack you have 9 attacks that deal 1d4 con damage (22.5 con damage average). While ~CR20 level foes will have a bit more con than that, every 2 points does effective damage equal to their HD).
Downside: This only comes online at level 13 and is of questionable power on anything immune to con damage.