I am still new player, 1st account 6 week old, 2nd account 4 week old.
I saw lot of advice on how to spent gems but no one seem to suggest to use gem for heroes rooster size upgrade early, Here why I think that is a good first use of gems:
On both account, I spent 250 gem to get the 5 first heroes rooster size upgrade for 25 more heroes space.
Space is not an extra when you need to keep 30 heroes for war and to get the most of your feeding using 10x same color 1* and 2*.
I know most people feed same color mix of 1* and 2*, give average of 30%(5x1* + 5x2*) special skill increase, but I use another strategy, I use 10x1* or 10x2* of same color and I keep the trainer heroes, here why:
You want a heroes special skill to reach it’s max before it get it’s max ascension-level, this is problematic mostly with 3*.
10x1* same color special skill increase is a “low” 20%, but you can still get it, it won’t raise much your hero XP meaning it give you more try until it’s fully leveled.
10x2* give a bigger experience boost but raise special skill increase chance to 40%, we are almost talking about a coin flip, which is a great chance to raise special skills.
With a big heroes rosters space, keep the copy of your 3*(or higher) to increase special skill too, you can use 3x(same heroes) (75%) + 6x2* (24%) and 1x1* (1%)(same color) and get a 100% chance spacial skill increase.
If you can get an extra 4x(same heroes) use only the 4 to get a 100% special skill increase, that’s a very good tips for the 3* you don’t level yet while you get them out of tc13.
I strongly suggest not to use the 3* heroes with special skill increase chance under 100% as bad luck will feel like you wasted them, unless you get to the point where it does not matter anymore, or for something like 2xsame heroes 50% + 8x 3*same color 48% = 98% chance
Keep in mind that you don’t need higher special skill than 8 minus ascension left to be done as ascension is almost guaranteed special skill increase(some report it can fail).
Keep your trainer heroes to finish leveling a heroes that have special skill maxed. Doing so you reduce the chance to get a fully level heroes that have only special skill around 4 or 5 and need to spend more heroes to it, losing the XP only to get only special skills increase.
Trainer heroes are also good to finish xp level up of 4* and 5* heroes you will get in the future as many other suggest as for them special skill increase is less problematic.
I been buying the next heroes rooster size upgrade (100 gem each for the next 5 heroes size boost) when I needed them, I will keep doing it based on my needs.
I decided not to use the gems to go for 1x elemental summon right away, maybe removing the chance to get a 5* soon, still might get one out of a free epic summon token… my tc13, on fist account, already provided 2x4* and many 3* so I am not in hurry for 5* and I lack the ascension material anyway. tc20 will ultimately provide some 5* at some point in the future and I will probably have more of the required ascension material when it will happen.
Gems for epic troops?:
On my first account I got lucky and got got 2x4* troops from epic troops summon token and a few 3* troops, on my 2nd account I was not lucky and only got only 1x3* troops yet, so I decided to keep stacking the gems to possible use of the 10x epic troops summon, 1600 gems to get 10 for the price of 8 single(200 gem each). I might use that only ONCE if I still lack too much better troops once I get that amount of gems (free to play take some time to get there), If I get better troops before I got the gems, then I will still be able to use them elsewhere like the most recommended 10x elemental summon of the color of the HoTM in coming months.