i have no problems with infinite combos personally. as long as you don't drag the game out and end it quickly its perfectly fine. just don't take half an hour tinkering. explain how your gonna kill everybody, check for responses, if no responses go to the next game.
I play it in Feather, the Redeemed. it comes in super handy when you want to keep recurring the same spells over and over again while also drawing new cards. I guess the usefulness of the tower depends on the deck its being used for
Maybe 5 color elementals? Animar, Soul of Elements could be super strong in the 99. it covers the cost reduction for generic mana and It can get huge fast.
i play Krenko, Mob Boss for red. goblin combo gets stupid fast but opponents will wisen up and krenko will die. as for green I play Rishkar, Peema Renegade its a +1 counter build that likes to ramp out huge critters
Mentor of the Meek
Path to Exile
Wall of Glare
Fiend Hunter
Monastery Mentor
Blue
Talrand, Sky Summoner
Narset's Reversal
Brainstorm
Counterspell
Baral, Chief of Compliance
Black
Erebos, God of the Dead
Demonic Tutor
Liliana of the Veil
Dark Ritual
Gray Merchant of Asphodel
Red
Krenko, Mob Boss
Purphoros, God of the Forge
Goblin Sharpshooter
Young Pyromancer
Blood Moon
Green
Rishkar, Peema Renegade
Kalonian Hydra
Birds of Paradise
Food Chain
Green Sun's Zenith
Multi
Prossh, Skyraider of Kher
Feather, the Redeemed
Terminate
Nicol Bolas
Dack Fayden
Artifact
Phyrexian Altar
Skullclamp
Isochron Scepter
Ashnod's Altar
Extraplanar Lens
Land
Urborg, Tomb of Yawgmoth
Mutavault
Maze of Ith
Phyrexian Tower
Oran-Rief, the Vastwood
turn 1: Mountain
turn 2: Mountain,Goblin Lookout
turn 3: Mountain, Ashnod's Altar
turn 4: Mountain, Krenko, Mob Boss
turn 5: Mountain, Staff of Domination. activate krenko for 2 goblin tokens, sac both tokens to altar and use the remaining two mountains to cast Siege-Gang Commander, sac 2 of the tokens to untap krenko with the staff and repeat to produce infinite colorless mana and infinite goblins. I then used Staff of Domination to draw through my deck until I hit Phyrexian Altar to generate red mana and killed everyone with Siege-Gang Commander