When is the best time to activate Glyph of Fortification on T3 Buildings?

I was in a game where we got team wiped on the last team fight, and the enemy team was trying to take down mid Tier 3 Towers and Barracks. I proceeded to activate glyphs when the tower was about 1/3 health. Then one of my teammates said that it was the wrong timing and it should be used when they start trying to take the barracks. We later on won the game but that made me wonder, was my teammate right?

The Tower Argument

The way I see it, the tower gets 100% concentrated attacks from both enemy creeps and heroes and is the last line of defense before the barracks become vulnerable. This means that the glyphs would soak up more concentrated damage in that 5 seconds than the damage on barracks (which may potentially be split on the two barracks if the enemy isn't smart about it). The tower basically has twice the armor than barracks (more than 2x for ranged) and slightly more health, so to me, the better strategy is to preserve the best defense and block concentrated damage.

The Barracks Argument

On the other hand, activating glyphs on the barracks also seems to makes sense because it gives 5 seconds of blocked damage on weaker buildings where it otherwise would have melted in 3 seconds or less. Also the hope that they will attack separate buildings after the tower is gone is not a very good argument. So, which is better?

More Situational Context:

• 3 of us were about 15 seconds or less from respawning, so using glyphs was semi-viable
• This would be the first T3 tower/rax take down attempt on our base (other lanes were still up)
• Enemy team was 5 man during the take down

Solution 1:

Ask yourself this question : Will using the Glyph save the tower or just delay its fall ?

• If the tower is going to fall anyway don't waste the glyph on the tower but save it for the weaker buildings. Even though the Melee Barrack regenerates life over time, it's better to avoid damage anyway. In your situation with 5 heroes down, chances are the enemy won't back up if you activate the Glyph for the tower, concider this tower lost and use the Glyph if they push further so you can temporize while you respawn.

• If you are sure that you can save the tower then use the Glyph. If you have some allies in the base that can slow down the push of the enemy team (like powerful AoE spells), use them to clear the creep wave and use the Glyph to temporize the enemy attacking the tower, you will gain 30 second until the next wave and you should have respawned by then.

Usually Glyphs either temporize while you wait for respawn/position to defend or try to dissuade the enemy team from pushing if the timing with their creep wave isn't good (e.g. all their creeps just died to the tower or a spell and they try to persue their push). In any situations, avoid giving away Tier 3 or Barracks if you can avoid it. It's a huge advantage for the enemy team and an opening in your base the next time you lose a teamfight.

Solution 2:

I kind of disagree with WizLiz here, so i'll give you my point of view/answer.

The tower has indeed more health/armor, and also has more damage.

We assume that you need about 10 or so seconds to get back to the tower, you'll need to glyph indeed, and you should always glyph on the tower. The tower will deal damage and maybe kill creeps or damage heroes, which racks won't do. It's not much, but it's always better than no damage at all.

On top of that, (and we still assume you need those 5 seconds of glyph), wether your t3 or racks hold 5 more seconds, you still need those 5 more seconds. So... you're better off having a glyphed tower and damaged rax than a dead tower and... more than likely damaged racks. My point remains the same, 5 seconds here or there doesn't really matter, it's just better to have damage going while it's happening.

Now, all that being said, if you KNOW* that you're gonna lose both tower and racks (because 4 or you are dead for >30 sec), you should NOT glyph, like WizLiz said, because you'll probably need it really soon after for another push on T4 or another T3.