as for visual aspects , indeed Colosseum would look better after teleport , maby raise some kind of walls between which you must fight .
in what regards the functionality , it's very good as it provides that debuff and by -100% enemy defence means also a higher chance to hit , that is very welcomed if you skip the annoying solar flare (incarnation boost for attack rating)) . for big / dangerous packs/single targets i always jump with colosseum first then use retaliate for the rest of the fight . i keep it as 1-pointer since the duration is almost the same as the timer , and there is no need for a lower timer , while the skillpoints got better places to go than to be dumped there
the holy paladin only got boosted slightly in therms of killspeed, as retaliate and plague deal a bit more damage than they used too . Also , the replacement of hammerstrike with divine judgment is not impressive at all . the build lacks a single target killer in the tree , or a conversion to something else that is not magic damage (we got retaliate for magic damage why on earth would we want the other skill in that tree do the same ?) . And for that you still need heavy procs on switch gear in order to be efficient (
The Flying Anvil

The Flying Anvil
Great Maul (4)
Two-Hand Damage: (14 - 17) to (19 - 41)
Required Level: 11
Required Strength: 117
Item Level: 29
Strength Damage Bonus: (0.16 per Strength)%
20% Attack Speed
+(1 to 20) to Maximum Damage
+(24 to 43)% Enhanced Damage
+1 to Hammertime
+(16 to 25) to Strength
Elemental Resists +(11 to 15)%
(11 to 15)% Bonus to Defense
Socketed (2)
Two-Hand Damage: (42 - 47) to (73 - 98)
Required Level: 29
Required Strength: 168
Item Level: 40
Strength Damage Bonus: (0.16 per Strength)%
40% Attack Speed
+(21 to 40) to Maximum Damage
+(64 to 83)% Enhanced Damage
+(4 to 8) to Hammertime
+(36 to 45) to Strength
Elemental Resists +(16 to 20)%
(21 to 25)% Bonus to Defense
Socketed (4)
Two-Hand Damage: (93 - 102) to (153 - 193)
Required Level: 48
Required Strength: 326
Item Level: 67
Strength Damage Bonus: (0.16 per Strength)%
60% Attack Speed
+(31 to 60) to Maximum Damage
+(104 to 123)% Enhanced Damage
+(10 to 14) to Hammertime
+(56 to 65) to Strength
Elemental Resists +(21 to 25)%
(31 to 35)% Bonus to Defense
Socketed (5)
Two-Hand Damage: (109 - 119) to (209 - 262)
Required Level: 55
Required Strength: 640
Item Level: 85
Strength Damage Bonus: (0.16 per Strength)%
80% Attack Speed
+(41 to 80) to Maximum Damage
+(124 to 143)% Enhanced Damage
+(15 to 20) to Hammertime
+(66 to 75) to Strength
Elemental Resists +(26 to 30)%
(36 to 40)% Bonus to Defense
Socketed (6)
/ a spear in ealry-mid game)