Death splinter is all about debuffs, just look at the available summoners, not to mention all the debuffs from the monsters. If you don't know yet, debuffs does stack. To be good at using death, you have to be well versed at predicting your enemy, failure to do so puts you at a huge summoner disadvantage.
Against melee compositions
Death splinter does well against melee compositions (like the famous life sneak composition), due to the variety of thorn monsters and melee debuffs available.
Against ranged compositions
Unlike magic and melee debuffs, silver death is a bit lacking in counters with only summoners being available. Although Contessa does well in low mana battles, it is not advised to be used against stronger ranged compositions like Yodin Zaku. I would recommend using other splinter-summoners like Water-Lir Deepswimmer and Life-Peakrider instead. Mimosa does well on opponents that tend to split damage and pesky heals since I'm not a fan of monster based affliction(50% chance).
Against magic compositions
Death splinter has very strong anti-magic compositions available, as such a natural counter against the current magic meta. One thing to note here is that Rotwell will most likely still lose against Mimosa in high mana battles even in an all out magic composition.
And finally, we have Dark Ha'on, the usual focus of my own compositions due to its power when combined with correct debuffs.
Explanation of use:
Sample 1:
https://splinterlands.com/?p=battle&id=sl_348c2a0416f0d4ea5fc05eb575bfebd0
A common mistake when using Ha'on is placing it on the first slot, its damage is pretty weak, and its only true purpose is that of a meatshield for the most part. Putting it in the first slot almost guarantees that it will die due to the strain of heavy melee hitters attacking it as well. Instead you can put Ha'on in slot two, and something like a thorn unit(since Ha'on will soak the ranged and magic damage) or a heavy hitter like Undead Rexx in the first slot.
Sample 2:
https://splinterlands.com/?p=battle&id=sl_b4604c02724de1fa05931324cc715fe4
Having Ha'on -a taunt unit guarantees that the heavy hitter, the case of sample 2 being the Undead Rexx several hits against the enemy, this makes up for the fact that it's not all that tanky.
Things to note:
As it stands debuff strats will not be applicable in modern for the most part, as most debuff monsters are non-modern.