This is an optimized build order from PiG's first Terran Bronze to GM series, the Platinum ranked Safe Terran MECH video. While he claims you can use it against all three races, I'd recommend this particular style of harass against Terran and Zerg.
We start with a basic 1 gas expand. You get 2 Marines, a Cyclone, and a Siege Tank for early defense before rushing for your BC. Then you go into Tank-Hellbat mech. It's a pretty easy build with some very low APM harass. It is relatively safe, but we are pushing for a 5 minute CC off a single Factory, so we're going to be cutting it close defensively against very aggressive openings.
If the in-game times look funky, I did this build on the Slower game speed in order to nail the build. Uploading the replay to SpawningTool automatically adjusted the timer. Regardless, the supply counts are correct.
12 | 0:00 | | |
13 | 0:12 | | |
14 | 0:17 | | |
14 | 0:24 | | |
15 | 0:38 | | |
16 | 0:39 | | |
16 | 0:44 | | Then send 17th SCV to scout |
16 | 0:50 | | |
17 | 1:02 | | |
18 | 1:15 | | |
19 | 1:25 | | |
20 | 1:26 | | |
20 | 1:45 | | |
20 | 1:56 | | |
20 | 2:00 | | |
21 | 2:02 | | |
22 | 2:09 | | |
22 | 2:12 | | |
23 | 2:17 | | Delayed for faster Factory, Marine, and Refinery |
23 | 2:22 | | Then swap the Factory onto the Tech Lab |
23 | 2:38 | | |
24 | 2:46 | | |
24 | 2:49 | | |
28 | 2:58 | | |
29 | 3:08 | | |
29 | 3:09 | | |
30 | 3:19 | | @100%, swap the Starport onto the Tech Lab |
35 | 3:31 | | |
36 | 3:38 | | |
36 | 3:40 | | Last Marine |
39 | 3:59 | | |
41 | 4:03 | | |
45 | 4:28 | | |
53 | 4:41 | | Second Tank can siege in the main |
58 | 4:57 | | Make this in the main |
59 | 5:06 | | |
60 | 5:13 | | Continuous Tank production |
65 | 5:25 | | Build this on the first Tech Lab |
67 | 5:36 | | This will swap onto the Starport Reactor coming up |
67 | 5:37 | | |
67 | 5:40 | | |
69 | 5:50 | | Swap this onto the next Starport Reactor |
69 | 5:56 | | Both with tech labs |
72 | 6:09 | | |
73 | 6:15 | | |
75 | 6:23 | | |
78 | 6:29 | | Continuous Hellion production |
82 | 6:34 | | |
82 | 6:36 | | And land 3rd CC on location |
87 | 6:47 | | |
87 | 6:48 | | From here I just decide to pump units |
156 | 8:35 | | You can take this sooner if you want |
167 | 8:54 | | |
167 | 8:55 | | @100% Research +2 Weapons |
173 | 9:05 | | |
179 | 9:10 | | Once 4th base gets saturated you'll need more production |
187 | 9:29 | | |
190 | 9:31 | | |
190 | 9:37 | | I max out around here so I spent money on more Factories |
193 | 9:48 | | |
198 | 10:00 | | |
198 | 10:18 | | |
198 | 10:21 | |
If you're having trouble with swapping around your addons, just remember that your first 6 Factories have 2 Reactors and 4 Tech Labs, with your Starport having an additional Reactor.
The 4 minute bunker timing is crucial in holding a lot of the early aggressive timing attacks, especially since you only get 4 Marines, 1 Cyclone, and 1 Siege Tank before your Factory production kicks in. Sometime around this 4 minute mark is when you can send your Cyclone to patrol the air-exposed edge of your main to catch drops.
Battlecruiser pops out at 5:32. While I'd recommend flying over to your opponent's base and hitting at the 6:20ish mark at their main, if you wanted to hit 45 seconds sooner and if your Fusion Core goes unscouted, feel free to scan in the main and hit at 5:35.
Against Terran, at a certain point after Platinum you're going to be running into standard Reaper-Hellion-Raven TvT.
A well timed build order from your opponent should have enough Raven energy to cast Interference Matrix on your BC, but you should still get a decent amount of work done with your harass, or at the very least get your opponent to stay at home and to build a few too many Missile Turrets.
And like any other TvT with a lot of Siege Tanks, you'll want to gain control of the skies.
Against Zerg, you can and probably should skip the early Cyclone and instead go straight for a Siege Tank. I've gotten away with not making a second Siege Tank against very greedy players, but with the number of early Roach timings players are using in the matchup, better to be safe than sorry. The only thing you'd want an early Cyclone for in this matchup is to combat Ravagers poking at your natural and at your main wall.
If do you scout your opponent going for early Roaches and if they're posturing a sub 45 Drone Roach Ravager Ling all in, it's better to pop out Banshees instead of the Battlecruiser.
Against Nydus rushes and other spooky early aggression, you'd be encouraged to delay the third CC and to more quickly get up your second and third Factory. 2 Tech Labs and constant Siege Tank production should help immensely and be a much much safer option if you choose to go that route.
Against Protoss, the BC harass can be relatively futile against the standard 2gate Blink build, since Blink and six Stalkers are finished over 30 seconds before the BC pops out. Still not the worst harass you could do, but expect the BC to serve as more of a distraction tactic than a means of economic damage.
Same as against Nydus worms, you may want to delay the third CC in order to better defend against your opponent Blinking into your main with 6 Stalkers just before your BC finishes. It shouldn't seem too too scary since you'll have your second Tank Sieged in the main, but 6 Blink Stalkers and an Observer can be really annoying before they get recalled back.
Once you scout your opponent's Robotics Bay, add in Liberators and/or Ravens to help deal with the Disruptors.