Beat Down (4e Optimized Character Build)
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This build is designed to knock things down. Frequently. This is a hybrid Fighter/Warden.
Player's Handbook, Player's Handbook 3, Martial Power, Martial Power 2, Primal Power, Numerous Dragon Magazine Publications
 Game Rule Components
Craghammer, Heavy Shield, Iron Armbands of Power
Starting Ability Scores (Before Racial Adjustments): Str 17, Con 16, Dex 10, Int 10, Wis 11, Cha 8
Race (Templates): Human is recommended.
Starting Racial Traits: Bonus Feat, Bonus Skill, Human Defense Bonus, Bonus At-Will Power
Bonus Feat: Bloodied Spear
Level 1: Hybrid Talent (Fighter Armor Proficiency)
Level 2: Weapon Focus (Hammer)
Level 4: Weapon Proficiency (Craghammer)
Level 6: Thunder Hammer
Level 8: Crushing Guardian
Level 10: Kulkor Battlearm Student
Level 11: Versatile Expertise
Level 12: Crippling Crush
Level 14: Staggering Challenge
Level 16: Hammer Shock
Level 18: Hammer Rhythm
Level 20: Unbalancing Shield Shove
Level 21: Dazing Fury
Kulkor Arms Master
I recommend replacing the feat you want the least of these with headsman's chop for a +5 damage bonus to your attacks against prone enemies.
This build allows you to knock a creature prone with opportunity attacks (Staggering Challenge feat), make an opportunity attack when you knock a creature prone (Kulkor Arms Master Paragon Path), and once per round either knock a creature prone or deal 2d8 extra damage to a prone creature (Perfect Guardian Epic Destiny). The other feats offer many bonuses to hammer attacks including rattling and extra damage. When reacting with Warden's Fury you will also daze creatures.
 Munchkin-Size Me
The dual marking ability of this build is very useful. You will also inflict more damage with hammer attacks while in Guardian Form.
 Side Notes
While choosing powers lean towards powers that knock creatures prone. This will allow you to knock a creature prone with you first attack, and immediately attack it with a melee basic as a free action dealing 2d8 extra damage and still leaving your opportunity action available for defending.
This class is limited to affecting creatures that are capable of being knocked prone. There are still plenty of hammer bonuses to make it a well rounded character but the best part of the build will be useless against creature that have no prone position. This is also an Epic Level build and may not be effective at lower levels.