There is no correlation between Duration and Tower Damage. Some has higher Duration, some has higher Tower Damage. Objects are grouped into clusters (marked with different colors) based on close values of Duration and Tower Damage.
Duration Tower Damage
Ancient Apparition 2535 19.37
Axe 2481 39.94
Bane 2434 22.83
Bloodseeker 2475 111.73
Bristleback 2476 79.89
Centaur Warrunner 2447 60.62
Clockwerk 2457 20.96
Crystal Maiden 2437 16.01
Dark Seer 2447 30.96
Dark Willow 2487 41.75
Disruptor 2435 11.31
Doom 2434 34.36
Earthshaker 2486 43.37
Elder Titan 2493 48.81
Ember Spirit 2430 67.80
Enchantress 2447 62.21
Enigma 2465 43.93
Faceless Void 2478 106.01
Grimstroke 2450 17.54
Gyrocopter 2462 48.79
Hoodwink 2483 33.12
Invoker 2469 97.96
Jakiro 2459 63.28
Keeper of the Light 2433 14.83
Kunkka 2481 69.20
Lich 2462 14.22
Lina 2470 92.61
Lion 2468 12.20
Mars 2430 45.70
Mirana 2442 47.77
Necrophos 2420 45.41
Nyx Assassin 2462 21.15
Ogre Magi 2437 40.46
Pangolier 2449 51.68
Phoenix 2443 29.03
Primal Beast 2437 36.81
Puck 2431 63.51
Pudge 2427 25.82
Queen of Pain 2458 75.77
Razor 2486 71.71
Riki 2472 58.09
Rubick 2462 15.08
Sand King 2491 26.82
Shadow Demon 2471 23.02
Silencer 2465 47.66
Skywrath Mage 2455 20.66
Slardar 2438 57.69
Snapfire 2437 47.53
Sniper 2526 130.33
Spectre 2534 86.95
Spirit Breaker 2423 30.79
Storm Spirit 2444 71.61
Techies 2490 40.16
Tidehunter 2438 40.51
Timbersaw 2430 55.72
Tinker 2465 7.95
Treant Protector 2424 36.25
Tusk 2411 31.33
Undying 2418 25.80
Venomancer 2457 36.33
Viper 2515 92.06
Warlock 2442 67.61
Windranger 2466 111.42
Winter Wyvern 2466 50.74
Witch Doctor 2467 15.26
Zeus 2526 26.64
Duration Tower Damage
Abaddon 2372 137.16
Alchemist 2380 130.37
Anti-Mage 2423 163.65
Arc Warden 2445 177.63
Chaos Knight 2402 125.44
Clinkz 2394 184.70
Death Prophet 2430 90.43
Dragon Knight 2442 118.23
Drow Ranger 2493 164.50
Huskar 2371 123.02
Juggernaut 2397 168.61
Legion Commander 2397 134.07
Leshrac 2437 104.40
Lifestealer 2406 147.03
Luna 2402 177.72
Medusa 2484 175.67
Monkey King 2409 114.40
Morphling 2365 185.86
Muerta 2477 160.78
Naga Siren 2399 183.52
Nature's Prophet 2436 160.41
Night Stalker 2416 88.27
Outworld Destroyer 2435 111.90
Phantom Assassin 2423 98.40
Phantom Lancer 2435 153.65
Pugna 2414 95.19
Shadow Fiend 2389 192.67
Shadow Shaman 2443 82.66
Slark 2408 130.27
Sven 2434 163.95
Templar Assassin 2385 155.75
Terrorblade 2410 220.46
Tiny 2427 89.54
Troll Warlord 2420 197.70
Underlord 2420 79.11
Ursa 2441 91.58
Void Spirit 2396 110.24
Weaver 2480 144.88
Wraith King 2419 142.27
Duration Tower Damage
Broodmother 2272 169.21
Lone Druid 2270 311.94
Lycan 2305 207.49
Meepo 2263 219.44
Visage 2310 185.02
Duration Tower Damage
Batrider 2396 22.20
Beastmaster 2328 94.63
Bounty Hunter 2388 33.21
Brewmaster 2389 89.11
Chen 2276 94.54
Dawnbreaker 2399 56.91
Dazzle 2399 18.67
Earth Spirit 2391 18.76
Io 2280 33.57
Magnus 2391 81.81
Marci 2372 81.62
Omniknight 2364 60.04
Oracle 2361 13.02
Vengeful Spirit 2400 25.26